Protective conditioning against GVHD and graft rejection after combined organ and hematopoietic cell transplantation

We have performed combined organ and hematopoietic cell transplantation using a similar conditioning regimen in mice and humans. In the mouse model of MHC-mismatched combined heart and marrow transplantation, we compared conditioning of BALB/c hosts with total lymphoid irradiation (TLI: 10 doses of 240 cGy each) targeted to the spleen, lymph nodes and thymus to conditioning with a single dose of sublethal total body irradiation (TBI; 450 cGy). Conditioning also included three injections of anti-thymocyte serum (ATS), in both groups. C57BL/6 heart grafts, marrow cells and blood mononuclear cells were transplanted 24 h after the completion of irradiation. Blood mononuclear cells were added to the marrow cells to engender severe graft versus host disease (GVHD) that is present after combined organ and hematopoietic cell transplantation in humans given non-myeloablative conditioning. Both TLI and TBI conditioned groups accepted the organ grafts and became stable chimeras. However, the TBI group all died of GVHD during the 100-day observation period. The TLI group survived during the same period without clinical signs of GVHD. These hosts were tolerized to the donor organ grafts, since third party grafts were rejected rapidly when transplanted after 100 days. When NK T-cell-deficient CD1d(-/-) BALB/c hosts were used instead of wild-type hosts in the TLI/ATS conditioned group, then all hosts survived but all rejected the organ grafts and almost all failed to develop stable chimerism. None developed GVHD. Since host NK T cells were required for graft acceptance and NK T cells are activated after recognition of CD1d on antigen presenting cells, we compared heart and marrow graft survival from wild-type versus CD1d(-/-) donors after transplantation to TLI and ATS conditioned wild-type hosts. Whereas marrow and heart grafts from wild-type donors were accepted, almost all grafts from CD1d donors were rejected. Grafts from control Jalpha18(-/-) donors that were NK T cell deficient but expressed CD1d were all accepted. The results indicate that host NK T cells facilitate graft acceptance by recognizing CD1d on donor cells. We applied the TLI conditioning regimen using 10 doses of 80 cGy each and 5 doses of rabbit ATG to human recipients of HLA-matched G-CSF "mobilized" blood mononuclear cell transplants for the treatment of leukemia and lymphoma [R. Lowsky, T. Takahashi, Y.P. Liu, et al., Protective conditioning for acute graft-versus-host disease. N. Engl. J. Med. 353 (2005) 1321-1331.]. Currently more than 100 transplants have been performed, and the incidence of acute GVHD has been about 4% when both MRD and MUD transplants are combined. Almost all recipients became complete chimeras after receiving grafts that contained 2-3x10(8) CD3(+) T cells/kg. In further studies, we applied the same TLI and ATG conditioning regimen to combined kidney and G-CSF "mobilized" blood stem cell transplantation from HLA-matched sibling donors. The hematopoietic grafts in the latter protocol were selected CD34(+) cells with 1x10(6) CD3(+) T cells/kg added back to the hematopoietic cells. Preliminary results indicate that stable mixed chimerism can be achieved using this protocol allowing for complete immunosuppressive drug withdrawal without GVHD or subsequent rejection episodes. Thus, conditioning with TLI based regimens can simultaneously protect against organ graft rejection and GVHD. Levels of chimerism are dependent upon the content of donor T cells in the hematopoietic graft.     

Interstitial pneumonitis in T cell-depleted bone marrow transplantation

The incidence of interstitial pneumonitis (IP) was reviewed in 80 consecutive patients who received allogeneic T lymphocyte-depleted bone marrow transplantation (BMT) for malignant and non-malignant diseases. Pretransplant conditioning used in malignant disorders included total lymphoid irradiation (TLI) 150 cGy x 4, total body irradiation (TBI) 200 cGy x 6, and cyclophosphamide (CY) 120 mg/kg. In non-malignant diseases conditioning included no TBI, but adjusted doses of TLI in addition to CY (severe aplastic anemia) or CY and busulfan (severe beta-thalassemia major). In the malignant group only one patient developed graft-versus-host disease (GVHD) grade I; IP developed in 12 out of 61 patients (19.7%) and IP-associated fatality occurred in five patients (8.2%). Cytomegalovirus (CMV) was associated with only two of the five fatal IP. In the non-malignant group there was no GVHD; one patient out of 19 (5.2%) had IP, which was fatal and not associated with CMV. These data indicate that fatal IP may appear in the absence of GVHD. The relatively low incidence of IP-related mortality in recipients of allogeneic T lymphocyte-depleted BMT suggests that although prevention of GVHD and elimination of drugs used for GVHD prevention may reduce the incidence of fatal pulmonary complications, other approaches have to be investigated for complete prevention of IP which still represents a major complication in patients with malignant hematologic disorders treated by allogeneic BMT.     

Early host CD8 T-cell recovery and sensitized anti-donor interleukin-2-producing and cytotoxic T-cell responses associated with marrow graft rejection following nonmyeloablative allogeneic bone marrow transplantation

OBJECTIVE: We developed a nonmyeloablative conditioning regimen for allogeneic bone marrow transplantation (BMT) followed by donor lymphocyte infusions (DLI) for treatment of chemotherapy refractory malignancies. Although the majority of patients who receive this regimen achieve lasting mixed or full allogeneic chimerism, approximately 30% show initial mixed chimerism followed by loss of the donor graft. These patients recover host hematopoiesis without significant cytopenias. To assess the role of immunologic rejection in graft loss, we compared T-cell recovery and in vitro alloresponses in six patients who lost their marrow graft to that in 16 concurrent patients with sustained donor chimerism. PATIENTS AND METHODS: Conditioning included pretransplant cyclophosphamide (150-200 mg/kg), thymic irradiation (700 cGy), and pre- and post-transplant equine antithymocyte globulin (ATG; ATGAM). HLA-identical related donor BMT was followed by DLI at approximately day 35 in patients without graft-vs-host disease. RESULTS: The group with transient chimerism showed significantly increased circulating host T-cell (median 416 cells/mm(3) vs 10 cells/mm(3), p<0.05) and CD8 T-cell numbers (354 cells/mm(3) vs 71 cells/mm(3), p<0.05) compared to the group with stable mixed or full donor chimerism within the first 100 days post-BMT. All DLI recipients who lost chimerism following DLI had greater than 80% recipient T cells at the time of DLI, whereas those with persistent chimerism had <60% host T cells. Graft rejection was associated with the development of a sensitized anti-donor bulk cytotoxic T-lymphocyte (CTL) response in 4 of 6 evaluated patients, compared to only 1 of 10 evaluated patients with sustained chimerism (p<0.05). Additionally, 3 of 5 evaluated transient chimeras showed high anti-donor CTL precursor frequencies in limiting dilution assays, and 3 of 4 evaluated transient chimeras showed high anti-donor interleukin-2 (IL-2)-producing T-helper (T(H)) cell frequencies. High anti-donor T(H) or cytotoxic T-lymphocyte precursors were not detected in sustained chimeras. CONCLUSION: These data indicate that loss of chimerism in patients receiving this nonmyeloablative regimen is due to immune-mediated rejection. This rejection appears to bemediated by recovering recipient cytolytic CD8(+) cells as well as IL-2-producing recipient T(H) cells. These data are the first to demonstrate sensitization of recipient anti-donor IL-2-producing cells in association with human marrow allograft rejection.     

Preliminary characterization of functional residual host-type T lymphocytes following conditioning for allogeneic HLA-matched bone marrow transplantation (BMT)

Host T lymphocytes which escape the effects of chemoradiotherapy may proliferate and lead to graft rejection, particularly in recipients of T cell-depleted bone marrow (BM) allografts. We studied the efficacy of several conditioning regimens including a new immunosuppressive regimen--total lymphoid irradiation (TLI) plus conventional chemotherapy and total body irradiation (TBI)--in abrogating residual host T lymphocytes as assessed by their ability to grow in vitro. A total of 38 patients were evaluated, 29 with hematologic malignancies, six with severe aplastic anemia (AA) and three with beta-thalassemia major (TM), of whom 32 were transplanted with HLA-identical T cell-depleted allogeneic BM from sibling donors. The median observation period was 15 months (range 3-21) posttransplant. Peripheral blood mononuclear cells (PBMC) taken from each patient on the day of transplant were cultured with interleukin 2 (IL-2) + phytohemagglutinin + irradiated donors' PBMC. Survival of cells for less than 2 weeks in vitro without proliferation was observed in 20 of 29 cases with malignancies and was considered negative. In this group only two leukemia (L) patients rejected the graft. Limited cell growth (less than or equal to 3 weeks) was seen in four L patients, two of whom showed early graft failure. Vigorous T cell growth (greater than 5 weeks, 62-96% CD4+ cells) was noted in eight cases (two L, four AA, two TM; none received TBI). In this group, sustained engraftment was observed in 7/7 patients who were treated with cyclosporin A (CSA) post grafting. Overall, we could demonstrate no clear correlation between graft failure and cell growth in vitro. The proliferating cells exhibited considerable cytotoxic activity in vitro against several tumor cell lines and were susceptible to pharmacological doses of CSA. The low incidence of continuous T cell proliferation in vitro in PBMC of L patients suggests that a combination of TLI, TBI and cyclophosphamide (CY) is highly effective in abrogating the host T cells and subsequent graft rejection. Since a rather small number of patients was included in this study, further studies are needed to determine the possible value of the in vitro T cell proliferation assay as a means for predicting graft failure.     

Immunological recovery after bone marrow transplantation for severe aplastic anaemia: A Brazilian experience

Abstract: Twenty-nine patients with severe aplastic anaemia (SAA) were submitted to bone marrow transplantation (BMT) and their immunological recovery analysed. Total lymphocyte counts, estimation of B lymphocytes, T lymphocytes and their subsets, natural-killer (NK) activity were performed. Cells with the CD8 + phenotype and NK activity were the first signs of immunological recovery, whereas the CD4 + subset recovered later in patients who suffered from acute graft versus host disease (GvHD) and infections. Acute and chronic GvHD, cirrhosis, rejection and HIV viral infection contributed to the persistence of the profound immunodeficiency status observed after BMT. Our results did not differ greatly from the others and confirmed that BMT may be performed in underdeveloped countries despite the difficulties it might pose.     

Mechanism of graft failure in HLA-matched and HLA-mismatched bone marrow transplant recipients

This report characterizes the mechanism of graft failure in five patients who received allogeneic marrow depleted of T cells in vitro using anti-T12 (CD6) monoclonal antibody and rabbit complement. This group of five patients represents all patients who experienced early graft failure in a larger group of 59 consecutive patients given T12 depleted marrow over a 5-year period. Although all patients received ablative pre-transplant conditioning including total body irradiation (12-14 Gy) graft failure was more frequent in patients without genetically HLA-identical donors (four of 11 patients) than in patients with HLA identical sibling donors (one of 48 patients). In patients without genotypically identical donors, graft failure was observed with variable degrees of genetic disparity including two patients with HLA haplotype-mismatched sibling donors, one patient with a phenotypically HLA-matched parental donor, and one patient with an HLA-matched unrelated donor. In patients with both HLA identical and non-identical donors, results of immunophenotypic analysis demonstrated that early graft failure was associated with peripheral lymphocytosis with T cells expressing CD2, CD3, CD5, CD6, CD8 and Ia antigens. Direct cytotoxicity studies demonstrated specific lysis of donor cells by circulating lymphocytes and further analysis indicated that effector cells were derived from the recipients and not donors. Taken together, these results suggest that these allogeneic grafts did not 'fail', but rather that residual host cytotoxic T cells were responsible for active rejection of donor marrow.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enhancement by dimethyl myleran of donor type chimerism in murine recipients of bone marrow allografts

A major problem in using murine models for studies of bone marrow allograft rejection in leukemia patients is the narrow margin in which graft rejection can be analyzed. In mice irradiated with greater than 9 Gy total body irradiation (TBI) rejection is minimal, whereas after administration of 8 Gy TBI, which spares a significant number of clonable T cells, a substantial frequency of host stem cells can also be detected. In current murine models, unlike in humans, bone marrow allograft rejection is generally associated with full autologous hematopoietic reconstitution. In the present study, we investigated the effect of the myeloablative drug dimethyl myleran (DMM) on chimerism status following transplantation of T cell-depleted allogenic bone marrow (using C57BL/6 donors and C3H/HeJ recipients, conditioned with 8 Gy TBI). Donor type chimerism 1 to 2 months post-transplant of 1 to 3 x 10(6) bone marrow cells was markedly enhanced by using DMM one day after TBI and prior to transplantation. Conditioning with cyclophosphamide instead of DMM, in combination with 8 Gy TBI, did not enhance engraftment of donor type cells. Artificial reconstitution of T cells, after conditioning with TBI plus DMM, by adding mature thymocytes, or presensitization with irradiated donor type spleen cells 1 week before TBI and DMM, led to strong graft rejection and consequently to severe anemia. The anti-donor responses in these models were proportional to the number of added T cells and to the number of cells used for presensitization, and they could be neutralized by increasing the bone marrow inoculum. These results demonstrate the potential of DMM to facilitate engraftment in unsensitized mice in which the host stem cells may compete with donor type cells; the use of DMM to create models in which mechanisms of immune rejection can be studied without interference due to stem cell competition; and that bone marrow allograft rejection may be overcome by increasing the bone marrow inoculum in these stringent models.     

New strategies in allogeneic stem cell transplantation: immunotherapy using irradiated allogeneic T cells

Recipients of T cell-depleted allogeneic bone marrow transplants have increased risks of relapse and graft rejection. The addition of donor T cells to the TCD allograft will decrease the risk of graft rejection but will increase the risk of graft-versus-host disease (GVHD). Relapse of leukemia or lymphoma following allogeneic bone marrow transplantation can be successfully treated with post-transplant infusions of donor lymphocytes. A relatively small number of donor T cells can have a profound anti-tumor effect and facilitate engraftment, but has an unpredictable potential for severe GVHD. An alternative to using viable immunocompetent donor immune cells to facilitate engraftment and to treat relapsed patients are donor lymphocytes that have been treated to limit their ability to proliferate and cause GVHD. T cells treated with irradiation retain cytotoxic activity against tumor cells and host immune cells. We have tested the hypothesis that allogeneic donor T cells treated with low-dose irradiation will facilitate engraftment and mediate an anti-leukemia effect in a mouse model of bone marrow transplantation. Multiple infusions of irradiated allogeneic donor lymphocytes in the peri-transplant period had graft-enhancing activity without resulting in GVHD. Murine recipients of irradiated allogeneic splenocytes and allogeneic bone marrow had stable donor-derived hematopoiesis without a significant contribution of irradiated donor cells to the T cell compartment. Removing T cells from the allogeneic splenocytes prior to irradiation largely eliminated their graft facilitating activity. Based upon the promising results of the pre-clinical murine studies, we initiated a phase I clinical trial of multiple infusions of irradiated allogeneic lymphocytes in patients who had relapsed after allogeneic BMT. Of 12 patients treated to date on this study, three have shown objective responses of their leukemia or lymphoma to multiple infusions of irradiated donor lymphocytes. We have initiated a new phase I clinical study to test the efficacy of multiple infusions of irradiated allogeneic cytotoxic T cells to facilitate engraftment in allogeneic transplantation. Successive cohorts of patients will be transplanted with allogeneic stem cells alone, or a combination of allogeneic stem cells and increasing numbers of irradiated allogeneic T cells. Irradiated allogeneic lymphocytes that retain short-term allo-specific cytotoxicity and lack the potential for clonal expansion in vivo can be considered as a novel form of immunotherapy with defined pharmacokinetics.     

Evolution of mixed chimerism after allogeneic bone marrow transplantation as determined on granulocytes and mononuclear cells by the polymerase chain reaction.

To evaluate the clinical relevance of mixed chimerism (MC) after allogeneic bone marrow transplantation (BMT), we developed a method based on amplification of DNA minisatellites by the polymerase chain reaction (PCR). This sensitive method by which MC lower than 1% can be detected is applicable to any patient-donor pair. Furthermore, because the analysis requires only small amounts of DNA, it allowed us to analyze samples early after BMT and during graft rejection. Results were obtained within 48 hours after blood sampling. Determination of MC in granulocytes (GR) and in mononuclear cells (Mnc) was performed in 20 patients treated for various hematologic malignancies. In patients who received untreated BM, recipient cells disappeared rapidly after BMT. In patients transplanted with T-cell-depleted BM, MC occurred in 15 of 16 cases. The percentage of host Mnc was always significantly higher than the percentage of host GR. The evolution of MC in patients who received T-cell-depleted marrow showed distinct patterns depending on whether patients remained in continuous complete remission, relapsed, or rejected their grafts. During complete remission, a relatively stable and significant number of host cells could be detected during the first 2 years after transplantation. Thereafter, their number decreased, but even after 4 years, low numbers of host cells could persist. When the patients relapsed, an increase in host Mnc was monitored without significant changes in the number of donor Mnc. In contrast, after the relapse, donor GR were no longer detected. Two cases of graft rejection were studied. Directly after the onset of the rejection, donor GR and Mnc disappeared rapidly. During that period, no significant changes in the number of host Mnc were detected.     

Graft rejection following HLA matched T-lymphocyte depleted bone marrow transplantation

Bone marrow graft rejection following HLA-matched bone marrow transplantation (BMT) for leukaemia has been a rare problem. However, with the introduction of T-lymphocyte depleted BMT, graft rejection is recognized as a new complication. At the Royal Free Hospital (RFH) in London T-depletion is achieved using two monoclonal antibodies with complement mediated lysis. The methodology was extended to other centres and in total 56 patients have received T-depleted, HLA matched BMT. Twelve of 56 patients have had graft rejection. At the RFH three of 41 (7%) patients have had rejection whereas at collaborating centres nine of 15 (60%) patients have had rejection. We have investigated these rejections in order to identify factor(s) responsible. Rejection was not restricted by patient or donor characteristics, nor disease status. Patient management, chemotherapy conditioning, efficiency of T-depletion, graft versus host disease (GvHD), and infection post BMT, were not consistently implicated. The major difference between the RFH and all other centres was in the radiotherapy (RT) conditioning: The RFH prescribed a single fraction of 7.5 Gy total body irradiation (TBI) whilst collaborating centres gave 10 or 12 Gy fractionated TBI. We conclude that the different incidence of rejection (7% v. 60%) relates primarily to the RT conditioning although the mechanisms(s) of rejection remain unknown. We conclude that where T-depleted BMT is used, compensation by more intensive RT conditioning is required in order to avert graft rejection.     

Impact of pretransplant conditioning and donor T cells on chimerism, graft-versus-host disease, graft-versus-leukemia reactivity, and tolerance after bone marrow transplantation

Graft rejection, mixed chimerism, graft-versus-host disease (GVHD), leukemia relapse, and tolerance are interrelated manifestations of immunologic reactivity between donor and host cells that significantly affect survival after allogeneic bone marrow transplantation (BMT). In this report, a mouse model of BMT, in which the donor and host were compatible at the major histocompatibility complex (MHC), was used (1) to examine the interrelationship of pretransplant conditioning and T-cell content of donor BM with regard to lymphoid chimerism and GVHD and (2) to determine how these factors affected graft-versus-leukemia (GVL) reactivity and donor-host-tolerance. AKR (H-2k) host mice were administered optimal or suboptimal total body irradiation (TBI) as pretransplant conditioning followed by administration of BM cells from B10.BR (H-2k) donor mice with or without added spleen cells as a source of T lymphocytes. Transplanted mice were injected with a supralethal dose of AKR leukemia cells 20 and 45 days post-BMT to assess GVL reactivity in vivo. The pretransplant conditioning of the host and T-cell content of the donor marrow affected the extent of donor T-cell chimerism and the severity of GVH disease. GVL reactivity was dependent on transplantation of mature donor T cells and occurred only in complete chimeras. Transplantation of T-cell-deficient BM resulted in the persistence of host T cells, ie, incomplete donor T-cell chimerism, even when lethal TBI was used. Mixed chimerism was associated with a lack of GVL reactivity, despite the fact that similar numbers of donor T cells were present in the spleens of mixed and complete chimeras. In this model, moderate numbers of donor T cells facilitated complete donor T-cell engraftment, caused only mild GVHD, and provided a significant GVL effect without preventing the subsequent development of tolerance after conditioning with suboptimal TBI. In contrast, severe, often lethal, GVHD developed when the dose of TBI was increased, whereas tolerance and no GVH/GVL reactivity developed when the T-cell content of the marrow was decreased.     

Unrelated donor bone marrow transplantation to treat severe aplastic anaemia in children and young adults

Alternative donor bone marrow transplantation (BMT) to treat severe aplastic anaemia (SAA) in children and young adults has been complicated by high rates of graft rejection and severe graft-versus-host disease (GVHD). We hypothesized that increased immunosuppression combined with T-cell depletion of the marrow graft would enable successful use of unrelated donor BMT in this disease. Preconditioning consisted of cytosine arabinoside, cyclophosphamide, and total body irradiation (TBI). T-cell depletion was with the anti-CD3 antibody T10B9. GVHD prophylaxis consisted of cyclosporine A. 28 previously transfused patients were transplanted. Nine donor/recipient pairs were HLA matched. As of 1 January 1996, 15/28 (54%) patients are alive, transfusion independent and well with a range of follow-up of 13 months to 8 years (median 2.75 years). Fatalities include all three patients with non-engraftment and all three patients with grade III/IV GVHD. Other fatalities were due to infections or therapy-related toxicity. The incidence ≥ grade II acute GVHD was 28%. These data show that in children with SAA who have failed immunosuppression, unrelated donor BMT offers a reasonable hope of long-term survival.     

Targeted pretransplant host lymphocyte depletion prior to T-cell depleted reduced-intensity allogeneic stem cell transplantation

Mixed chimaerism and graft rejection are higher after reduced-intensity allogeneic stem cell transplantation (RIST) with T-cell depleted (TCD) allografts. As host immune status before RIST affects engraftment, we hypothesized that targeted depletion of host lymphocytes prior to RIST would abrogate graft rejection and promote donor chimaerism. Lymphocyte-depleting chemotherapy was administered at conventional doses to subjects prior to RIST with the intent of decreasing CD4(+) counts to <0.05 x 10(9)cells/l. Subjects (n = 18) then received reduced-intensity conditioning followed by ex vivo TCD human leucocyte antigen-matched sibling allografts. All evaluable patients (n = 17) were engrafted; there were no late graft failures. At day +28 post-RIST, 12 patients showed complete donor chimaerism. Mixed chimaerism in the remaining five patients was associated with higher numbers of circulating host CD3(+) cells (P = 0.0032) after lymphocyte-depleting chemotherapy and was preferentially observed in T lymphoid rather than myeloid cells. Full donor chimaerism was achieved in all patients after planned donor lymphocyte infusions. These data reflect the importance of host immune status prior to RIST and suggest that targeted host lymphocyte depletion facilitates the engraftment of TCD allografts. Targeted lymphocyte depletion may permit an individualized approach to conditioning based on host immune status prior to RIST.     

Interleukin 2-activated killer cells in patients following transplants of soybean lectin-separated and E rosette-depleted bone marrow

During the early period following bone marrow transplantation before the immune system has reached full functional maturity, unprimed, nonspecific lytic systems may play a critical role as antiviral or antitumor effectors. The reconstitution of cells with this potential is of particular importance in recipients of bone marrow that has been depleted of mature T lymphocytes to prevent graft v host disease (GVHD). We examined the recovery of natural killer (NK) cells and interleukin 2 (IL 2)-augmented lymphokine-activated killer cells (LAK) in 48 patients at various intervals following transplantation of bone marrow depleted of mature cellular elements by treatment with soybean agglutinin and sheep RBCs (SBA-E- BMT). We found normal levels of both NK and LAK activity as early as 3 weeks following SBA-E- BMT. When compared with cells from controls, NK and LAK precursors from transplant recipients appeared to be activated in vivo in that freshly isolated peripheral blood mononuclear cells (PBMCs) from patients had an elevated cytolytic activity toward NK-insensitive targets and a more rapid response to activation by IL 2. In patients as well as controls, both LAK precursors and LAK effectors lacked antigens present on mature T lymphocytes (CD3, CD4, or CD8) but expressed antigens present on NK cells (CD2, CD16, and NKH1A). The LAK cells did not lyse either donor or host peripheral blood T cell targets. The activity of NK effectors but not LAK precursors survived the in vivo total body irradiation used for pretransplant conditioning in three patients studied. LAK precursors could be demonstrated as early as 18 days following transplant at a time when the bone marrow contained primarily donor- derived cells. Little or no LAK activity could be generated from cells of the SBA-E- BM graft itself, suggesting that LAK precursors differentiate rapidly from more primitive progenitors in the marrow graft. Thus, our data indicate that the NK and LAK lytic systems are among the earliest activities to recover during immune reconstitution following T cell-depleted BMTs.     

Immunologic effects of prophylactic donor lymphocyte infusion after allogeneic marrow transplantation for multiple myeloma

Reconstitution of T-cell immunity after bone marrow transplantation (BMT) is often delayed, resulting in a prolonged period of immunodeficiency. Donor lymphocyte infusion (DLI) has been used to enhance graft-versus-leukemia activity after BMT, but the effects of DLI on immune reconstitution have not been established. We studied 9 patients with multiple myeloma who received myeloablative therapy and T-cell-depleted allogeneic BMT followed 6 months later by infusion of lymphocytes from the same donor. DLI consisted of 3 x 10(7) CD4(+) donor T cells per kilogram obtained after in vitro depletion of CD8(+) cells. Cell surface phenotype of peripheral lymphocytes, T-cell receptor (TCR) V beta repertoire, TCR rearrangement excision circles (TRECs), and hematopoietic chimerism were studied in the first 6 months after BMT and for 1 year after DLI. These studies were also performed in 7 patients who received similar myeloablative therapy and BMT but without DLI. Phenotypic reconstitution of T and natural killer cells was similar in both groups, but patients who received CD4(+) DLI developed increased numbers of CD20(+) B cells. TCR V beta repertoire complexity was decreased at 3 and 6 months after BMT but improved more rapidly in patients who received DLI (P =.01). CD4(+) DLI was also associated with increased numbers of TRECs in CD3(+) T cells (P <.001) and with conversion to complete donor hematopoiesis (P =.05). These results provide evidence that prophylactic infusion of CD4(+) donor lymphocytes 6 months after BMT enhances reconstitution of donor T cells and conversion to donor hematopoiesis as well as promoting antitumor immunity.     

Durable engraftment of major histocompatibility complex-incompatible cells after nonmyeloablative conditioning with fludarabine, low-dose total body irradiation, and posttransplantation cyclophosphamide.

Treatment of leukemia by myeloablative conditioning and transplantation of major histocompatibility complex (MHC)-mismatched stem cells is generally avoided because of the high risk of graft rejection or lethal graft-versus-host disease (GVHD). This study shows that MHC-incompatible cells can engraft stably after nonmyeloablative conditioning with immunosuppressive chemotherapy and low-dose total body irradiation (TBI). Long-term mixed hematopoietic chimerism, clonal deletion of donor-reactive T cells, and bidirectional cytotoxic T-cell tolerance were achieved by transplanting MHC-mismatched marrow cells into recipients conditioned with pretransplantation fludarabine or cyclophosphamide (Cy), 50 to 200 cGy TBI on day -1, and Cy 200 mg/kg intraperitoneally on day 3. In this model, long-term donor chimerism was proportional to the dose of TBI or donor marrow cells. Pretransplantation fludarabine and posttransplantation Cy were both required for alloengraftment, but the drugs had additional effects. For example, fludarabine sensitized host stem cells to the toxicity of TBI, because animals conditioned with both agents had higher chimerism than animals conditioned with TBI alone (P <.05). Also, posttransplantation Cy attenuated lethal and nonlethal GVH reactions, because F(1) recipients of host-reactive, parental spleen cells survived longer (P <.05) and had lower donor cell chimerism (P <.01) if they received posttransplantation Cy than if they did not. Finally, delayed infusions of donor lymphocytes into mixed chimeras prolonged survival after leukemia challenge (P <.0001) without causing lethal GVHD. These results indicate that stable engraftment of MHC-incompatible cells can be induced after fludarabine-based, nonmyeloablative conditioning and that it serves as a platform for adoptive immunotherapy with donor lymphocyte infusions.     

Larger numbers of CD4(bright) dendritic cells in donor bone marrow are associated with increased relapse after allogeneic bone marrow transplantation

Relapse is the major cause of death after allogeneic bone marrow transplantation (BMT). This study tested the hypothesis that the numbers of donor mononuclear cells, lymphocytes, and CD34(+) cells influence relapse and event-free survival (EFS) after BMT. The study population consisted of 113 consecutive patients with hematologic malignancies who underwent non-T-cell-depleted BMT from HLA-matched siblings. Sixty-four patients had low-risk diagnoses (ALL/AML CR1, MDS RA/RARS, and CML CP1); 49 patients had high-risk diagnoses (all others). CD34(+) cells, T cells, B cells, natural killer cells, monocytes, and a rare population of CD3(-), CD4(bright) cells in the allografts were measured by flow cytometry. The CD3(-), CD4(bright) cells in bone marrow had the same frequency and phenotype as CD123(bright) type 2 dendritic cell (DC) progenitors, and they differentiated into typical DCs after short-term culture. Cox regression analyses evaluated risk strata, age, gender, and the numbers of nucleated cells, CD3(+) T cells, CD34(+) hematopoietic cells, and CD4(bright) cells as covariates for EFS, relapse, and nonrelapse mortality. Recipients of larger numbers of CD4(bright) cells had significantly lower EFS, a lower incidence of chronic graft-versus-host disease (cGVHD), and an increased incidence of relapse. Recipients of larger numbers of CD34(+) cells had improved EFS; recipients of fewer CD34(+) cells had delayed hematopoietic engraftment and increased death from infections. In conclusion, the content of donor CD4(bright) cells was associated with decreased cGVHD and graft-versus-leukemia effects in recipients of allogeneic bone marrow transplantation, consistent with a role for donor DCs in determining immune responses after allogeneic BMT.     

Anti-NK cell treatment induces stable mixed chimerism in MHC-mismatched, T cell-depleted, nonmyeloablative bone marrow transplantation

OBJECTIVE: To clarify natural killer (NK) cell-mediated resistance under cytoreductive conditioning and T cell-depleted bone marrow transplantation, we investigated the effects of host NK cell depletion on engraftment and induction of stable mixed chimerism. METHODS: BALB/c mice (H-2kd) were injected intraperitoneally with anti-asialoGM1 antibody (anti-NK Ab) on day -1. On day 0, they received total body irradiation (TBI) at a dose of 500 cGy, followed by intravenous infusion of 2 x 10(7) T cell-depleted (TCD) bone marrow cells from C57BL/6 mice (H-2kb). Early engraftment and chimerism were determined by the relative ratio of peripheral blood (PB) lymphocytes expressing either H-2kd or H-2kb on day +21. Long-term engraftment and chimerism were evaluated on PB and spleen by multicolor flow cytometry. RESULTS: Although no recipients treated with TBI alone showed engraftment, all the recipients conditioned with anti-NK Ab and TBI showed successful engraftment as well as a donor-dominant pattern of mixed chimerism in both PB and spleen. Spleen cells from recipients with mixed chimerism showed specific tolerance to both host and donor strains, but not to a third party (C3H/He). None of the reconstituted mice showed signs of graft vs host disease, and all survived up to day +330. CONCLUSION: These observations indicate that host NK cell depletion may be used to reduce the intensity of conditioning regimens for engraftment of TCD grafts, and can contribute to establishment of stable mixed chimerism in major histocompatibility complex-mismatched nonmyeloablative transplantation.     

Unrelated donor bone marrow transplantation for the treatment of Fanconi anemia.

Bone marrow transplantation (BMT) is the only known cure for the hematologic manifestations of Fanconi anemia (FA). Potential benefits of unrelated donor BMT for FA, however, have been severely limited by graft rejection and treatment-related mortality with resultant poor survival. Therefore, we evaluated the impact of potential prognostic factors on hematopoietic recovery, graft-versus-host disease (GVHD), and mortality in 98 recipients of unrelated donor BMT who received transplants between 1990 and 2003. Probabilities of neutrophil (89% vs 69%; P = .02) and platelet (74% vs 23%; P < .001) recovery were higher after fludarabine-containing regimens than nonfludarabine-containing regimens. Risks of acute GVHD (relative risk [RR], 4.29; P < .001) were higher with non-T-cell-depleted grafts. The day-100 mortality rate was significantly higher after nonfludarabine-containing regimens than fludarabine-containing regimens (65% vs 24%, respectively; P < .001). Corresponding 3-year adjusted overall survival rates were 13% versus 52% (P < .001). In addition, mortality was higher in recipients who were older (> 10 years), who were cytomegalovirus (CMV) seropositive, and who received more than 20 blood product transfusions before BMT. Based on these results, significant practice changes are suggested: use of a fludarabine-containing conditioning regimen in the context of T-cell-depleted marrow allografts, and earlier referral for transplantation prior to excessive transfusions in patients with marrow failure.     

Graft failure after T-cell-depleted human leukocyte antigen identical marrow transplants for leukemia: II. In vitro analyses of host effector mechanisms

To identify mechanisms potentially contributing to graft failure, 19 leukemic recipients of T-cell-depleted marrow transplants who failed to engraft following a transplant of HLA identical sibling marrow depleted of T cells by soybean agglutinin (SBA) and sheep erythrocytes (E) were evaluated. Peripheral blood mononuclear cells isolated at the time of failure were consistently of host origin, bearing the phenotype of suppressor T cells (CD3+, CD8+, Leu 7+). A direct cytolytic effect on 51Cr-labeled donor-derived target cells was not detected, a finding that contrasts with the donor-specific cytotoxic host T lymphocytes that have been regularly observed in patients rejecting HLA nonidentical SBA -E- BMTs. However, these host T cells did exhibit a strong and specific suppressive activity against the donor marrow CFU- GM in vitro. Furthermore, in contrast to prior findings in durably engrafted recipients of SBA -E- BMTs, the lymphocytes isolated prior to or at the time of graft failure lacked natural killer surface antigen expression and effector function.