Polyclonal reconstitution of human marrow after allogeneic bone marrow transplantation

Clonal dominance suggestive of reconstitution of marrow from small numbers of pluripotent hematopoietic stem cells has been noted in different experimental and clinical situations. Recipients of human allogeneic marrow transplants have not been previously studied to determine if clonal dominance occurs in this clinical setting. Clonal analysis of 20 allogeneic marrow transplant recipients was performed on DNA from peripheral blood neutrophils using restriction fragment length polymorphisms on the X chromosome. Similar studies were performed on 16 of the donors. To analyze the results further, recipients were paired with their respective donors. There was no evidence of shifts in cell populations contributing to the X chromosome inactivation patterns in recipient marrow grafts when compared with their respective donors. A mathematical model based on binomial statistics was adapted to estimate the numbers of reconstituting pluripotent hematopoietic stem cells. There was no evidence of clonal dominance suggestive of oligoclonal reconstitution in marrow grafts after allogeneic marrow transplantation. This does not preclude the possibility of oligoclonal reconstitution in other marrow transplant settings such as autologous transplantation.     

Phase I/II multisite trial of optimally dosed clofarabine and low-dose TBI for hematopoietic cell transplantation in acute myeloid leukemia

Clofarabine is an immunosuppressive purine nucleoside analog that may have better anti-leukemic activity than fludarabine. We performed a prospective phase I/II multisite trial of clofarabine with 2 Gy total body irradiation as non-myeloablative conditioning for allogeneic hematopoietic cell transplantation in adults with acute myeloid leukemia who were unfit for more intense regimens. Our main objective was to improve the 6-month relapse rate following non-myeloablative conditioning, while maintaining historic rates of non-relapse mortality (NRM) and engraftment. Forty-four patients, 53 to 74 (median: 69) years, were treated with clofarabine at 150 to 250 mg/m², of whom 36 were treated at the maximum protocol-specified dose. One patient developed multifactorial acute kidney injury and another developed multiorgan failure, but no other grade 3 to 5 non-hematologic toxicities were observed. All patients fully engrafted. The 6-month relapse rate was 16% (95% CI, 5%-27%) among all patients and 14% (95% CI, 3%-26%) among high-risk patients treated at the maximum dose, meeting the pre-specified primary efficacy endpoint. Overall survival was 55% (95% CI, 40%-70%) and leukemia-free survival was 52% (95% CI, 37%-67%) at 2 years. Compared to a historical high-risk cohort treated with the combination of fludarabine at 90 mg/m² and 2 Gy TBI, protocol patients treated with the clofarabine-TBI regimen had lower rates of overall mortality (HR of 0.50, 95% CI, 0.28-0.91), disease progression or death (HR 0.48, 95% CI, 0.27-0.85), and morphologic relapse (HR 0.30, 95% CI, 0.13-0.69), and comparable NRM (HR 0.85, 95% CI 0.36-2.00). The combination of clofarabine with TBI warrants further investigation in patients with high-risk AML.     

Long-term survival after marrow transplantation for paroxysmal nocturnal hemoglobinuria with aplastic anemia

Four patients with paroxysmal nocturnal hemoglobinuria and severe marrow aplasia were given marrow grafts either from allogeneic human-leukocyte-antigen-identical siblings (three patients) or from a syngeneic donor (one patient). The patients with allogeneic grafts were conditioned with regimens that included cyclophosphamide and had sustained and complete marrow engraftment; subsequent tests were negative for paroxysmal nocturnal hemoglobinuria. One patient developed chronic graft-versus-host disease that resolved over 4 years. The patient receiving a syngeneic graft received marrow infusion without preceding immunosuppression. He had prompt engraftment, and hematologic variables returned to normal. A Ham's test done at 3 years was negative, but a complement lysis sensitivity test done 10 years after grafting was positive; the patient, however, remains asymptomatic. All four patients are alive and well 4, 9, 10, and 12 years after transplantation. Paroxysmal nocturnal hemoglobinuria apparently can be treated successfully by allogeneic or syngeneic marrow transplantation without subsequent maintenance therapy.     

Inhibition of prostaglandin E2 restores defective lymphocyte proliferation and cell-mediated lympholysis in recipients after allogeneic marrow grafting

Prostaglandins are said to influence T and B cell function by inhibiting the generation of interleukin 2 (IL 2) and the formation of suppressor lymphocytes. After bone marrow transplantation, patients usually have a profound immunodeficiency that persists in recipients with chronic graft-v-host disease (GVHD) and generally resolves in long- term survivors without GVHD. In vitro tests of lymphocyte function such as allogeneic mixed lymphocyte culture (MLC) and cell-mediated lympholysis (CML) have been shown to be impaired in many patients. We postulated that prostaglandin E2 (PGE2) plays a role in the impaired in vitro tests. To test this hypothesis, we studied in vitro tests in the presence of PGE2 antagonists, indomethacin, and anti-PGE2 antiserum with cells from 22 short-term patients (less than 100 days postgrafting) and 32 long-term survivors with or without GVHD. Results show that blockade of PGE2 release by indomethacin and anti-PGE2 significantly (P less than .01) enhanced the MLC (+67%) and the CML responses (+10.5%) of cells from long-term survivors with chronic GVHD but not from those of long-term, stable recipients. No enhancement of MLC and CML activity was observed with cells from donors of long-term recipients. In patients shortly after marrow grafting, enhancement in the MLC was not significant. However, CML activity in this patient group was significantly increased (+12.5% in recipients with no GVHD, 8.5% in those with acute GVHD, P less than .01). Indomethacin also suppressed the activity of nonspecific suppressor cells in patients with chronic GVHD. When cells from patients with chronic GVHD were treated with recombinant IL 2 and IL 2 combined with indomethacin, it was possible to get an additional augmentation of lymphocyte proliferation after the addition of indomethacin to IL 2-treated cultures. Thus it is very likely that PGE2 inhibits T lymphocyte proliferation, not exclusively by inhibition of IL2 production or activity. We conclude that PGE2, among other factors, may play a role in the pathogenesis of the immunodeficiency after transplantation. PGE2 does not act primarily by interfering with IL2 but presumably by inducing a suppressorlike activity.     

Molecular cloning and in vivo evaluation of canine granulocyte-macrophage colony-stimulating factor

Canine granulocyte-macrophage colony-stimulating factor (caGM-CSF) was cloned and expressed to allow further investigation of GM-CSF in a large animal model. The cDNA is 850 base pairs (bp) long and encodes a peptide of 144 amino acids. The nucleotide and amino acid sequence homology between caGM-CSF and human GM-CSF (hGM-CSF) is 80% and 70%, respectively. A mammalian expression vector pCMV/CAGM was constructed and used to transfect COS cells for expression of caGM-CSF. Supernatant from transfected COS cells enriched with caGM-CSF was shown to have significant stimulating activity in granulocyte-macrophage colony forming unit (CFU-GM) assays of canine marrow. caGM-CSF, expressed from bacteria, was used to treat seven dogs at varying doses twice daily subcutaneously (sc) for 14 to 16 days. Circulating blood neutrophils and monocytes increased significantly. The increase in circulating eosinophils was variable. Thrombocytopenia developed during administration of caGM-CSF but corrected rapidly after cessation of treatment. Evaluation of survival times of 51Cr-labeled autologous platelets suggested increased consumption as the primary reason for thrombocytopenia. A species-specific GM-CSF will be a useful tool for hematologic or immunologic studies in dogs.     

Gynecological abnormalities following allogeneic bone marrow transplantation

Forty-four post-pubertal women were studied 261-4628 days after allogeneic transplantation to determine the nature and degree of gynecological abnormalities following bone marrow transplantation. Evaluations included pelvic examinations, exfoliative cytology, serum gonadotropin levels, direct preparations for micro-organisms, and microbial cultures. Pelvic abnormalities were detected in 35 of 44 (80%) women and resembled atrophic changes known to occur after ovarian failure. Findings included reduced vaginal elasticity and rugal folds, pale tissues, small vaginal, uterine and cervical size, atrophic vulvovaginitis, introital stenosis, and loss of pubic hair. Atrophic abnormalities were noted in 33 of 36 recipients of total body irradiation (TBI) compared to two of eight women not prepared with TBI (p = 0.02). Vasomotor symptoms were reported in 67% of TBI recipients compared to 38% of those not given TBI. Elevated serum gonadotropin levels suggested that TBI had caused the ovarian failure. Recognition of these gynecological abnormalities can lead to earlier hormone replacement, alleviating unnecessary discomfort and improving the well-being of the marrow transplant recipient.