Evidence that indefinite survival of small bowel allografts achieved by a brief course of cyclosporine or FK506 is not due to systemic hyporesponsiveness.

The immunological status of Lewis (LEW) recipients of indefinitely surviving (greater than 400 days) orthotopic Brown-Norway (BN) small bowel allografts was investigated 1 to 1 1/2 years after cessation of immunosuppressive therapy with either cyclosporine or FK506 and compared with recipients of syngeneic grafts. A normal proliferative response (as measured by a mixed lymphocyte culture) of recipient peripheral lymph node lymphocytes in response to the donor-specific (BN) and the third-party (ACI) antigen, was observed in all experimental groups. Cytolytic T cell generation (as measured by a standard 51Cr-release cytotoxicity assay) in response to the donor-specific (BN) and the third-party (ACI) antigen was observed also in all groups. A FACS analysis of allograft-recipient splenocytes showed no evidence for systemic lymphoid chimerism. BN or ACI skin grafts transplanted onto recipients of allogeneic and syngeneic small bowel grafts were rejected completely in 12-17 days, while the intestinal grafts remained functional. Immunohistologic evaluation of the allografts, using anti-BN class I and anti-Lewis class II monoclonal antibodies showed anti-BN staining on the epithelial and endothelial structures, whereas the mononuclear cells in the lamina propria stained positively with the anti-LEW monoclonal antibody. However, lymphoid depletion and scarring of Peyer's patches and mesenteric lymph nodes as well as focal obliterative mesenteric arteriopathy, indicative of an indolent chronic rejection, were observed. These data demonstrate that recipients of indefinitely surviving small bowel allografts remain immune competent and do not retain the intestinal graft on the basis of specific hyporesponsiveness to the donor antigens.     

Development of an antibody specific to major histocompatibility antigens detectable by flow cytometry after lung transplant is associated with bronchiolitis obliterans syndrome

BACKGROUND: Chronic allograft rejection manifested as bronchiolitis obliterans syndrome (BOS) is the leading cause of late death after lung transplantation. Although increasing evidence suggests an association between anti-human leukocyte antigens (HLA) antibodies and chronic rejection of kidney or heart allografts, the clinical significance of anti-HLA antibodies in lung recipients is less clear, especially in previously unsensitized recipients. The use of flow cytometry based panel reactive antibody (flow-PRA) provides a highly sensitive means to identify the development of de novo anti-HLA antibodies in lung recipients. METHODS: Flow-PRA testing was used to analyze the pre- and posttransplant sera in stable BOS free lung recipients who survived at least 6 months. Patients without prior sensitization as defined by a negative pretransplant flow-PRA were analyzed posttransplant for the presence of anti-HLA antibodies by flow-PRA. A proportional hazards model was used to determine the impact of anti-HLA antibody on BOS risk. RESULTS: Sera from 90 recipients at Duke University with negative pretransplant flow-PRA were tested by flow-PRA at various time points after transplant. Sera from 11% (10/90) of recipients were found to contain anti-HLA antibodies detectable by flow-PRA. Nine patients (90%) developed anti-HLA antibodies specific for donor antigens, and one patient developed anti-HLA class II antibodies, not specific to donor antigens. Among the nine patients with donor antigen specific antibodies, flow-PRA specificity analysis demonstrated eight were specific for class II antigens and one for class I antigens. In a multivariate model that controls for other BOS risk factors, a positive posttransplant flow-PRA was significantly associated with BOS grades 1,2, or 3 (hazard ratios [HR] 3.19; 95% confidence interval [CI]: 1.41-7.12, P=0.005) and BOS grade 2 or 3 (HR 4.08; 95% CI: 1.66-10.04, P=0.002). Four patients with de novo anti-HLA antibodies died during follow-up; all four had BOS. Among BOS patients, the presence of anti-HLA antibodies was associated with a significantly worse survival (P =0.05, log-rank test). CONCLUSIONS: Although uncommon, previously unsensitized lung transplant recipients can develop anti-HLA antibodies to donor class II antigens. The development of de novo anti-HLA antibodies significantly increases the risk for BOS, independent of other posttransplant events. Furthermore, de novo anti-HLA antibodies identify BOS patients with significantly worse survival. Additional studies are needed to determine if class II-directed anti-HLA antibodies contribute mechanistically to the chronic rejection process in lung recipients.     

Induction of transplantation tolerance in rats by spleen allografts. II. Evidence that W3/25+ T suppressor/inducer and OX8+ T suppressor/effector cells are required to mediate specific unresponsiveness

The results presented in this report demonstrate that T cells, isolated from AGUS rats bearing long-term (WAG X AGUS)F1 spleen allografts adoptively transferred to irradiated AGUS recipients could not mediate the rejection of WAG hearts but rejected PVG. A hearts in acute fashion. Further, unresponsive T cells were able to suppress the capacity of adoptively transferred (40 X 10(6) normal T cells to reject WAG but not PVG.A heart allografts. We also studied the role of W3/25+ and OX8+ T cells subsets in the maintenance of unresponsiveness. Isolated W3/25+ or OX8+ unresponsive T cells were not able to mediate acute rejection, but were less effective in prolonging WAG allograft survival than the unresponsive whole T cell population, suggesting that both W3/25+ Ts1 and OX8+ Ts2 subsets were required for effective suppression in vivo. When, however, unresponsive W3/25+ T cells were infused simultaneously with normal OX8+ T cells, they could produce indefinite survival of WAG heart allografts. These results indicate that the unresponsive state induced by (WAG X AGUS)F1 spleen allografts transplanted to AGUS rats is maintained by the interaction of W3/25+ T suppressor/inducer and OX8+ T suppressor/effector cells.     

Separation of the immune response genes for LDH-B and MOPC-173. III. Evidence that the failure of B10.BASR1 to respond to LDH-B is due to an antigen-presenting cell defect

Analysis of the immune response of a panel of intra-I-region recombinant mouse strains to LDH-B and MOPC-173 demonstrated that B10.ASR7 (H-2as3) and B10.BASR1 (H-2as4) failed to mount T-cell-proliferative responses to MOPC-173 and LDH-B, respectively. To localize the level of the immune response defect in the B10.BASR1 strain, B10.BASR1 macrophages were shown to be incapable of presenting LDH-B to immune responder B10.ASR7 T cells. These results were confirmed using alloreactivity-depleted and (B10.ASR7 X B10.BASR1)F1 immune T cells. Failure of these strains to respond was shown not to be the result of T cell suppression, because cyclophosphamide and anti-Lyt-2.2-plus-complement treatments did not restore responsiveness. Furthermore, B10.BASR1 macrophages were incapable of educating naive responder T cells in vitro to LDH-B--however, naive nonresponder B10.BASR1 T cells could be educated by responder macrophages to LDH-B in vitro. These results suggest that the failure of B10.BASR1 to respond to LDH-B reflects a defect at the macrophage-T cell interaction level, perhaps related to expression of unique I-A molecules created by intra-I-region recombinatorial events.     

Relationship between inducible H-2 expression and the immunogenicity of murine skin neoplasms. I. Evidence that the immunogenicity of ultraviolet radiation-chemically induced tumors is associated with their susceptibility to gamma-interferon-mediated enhancement of H-2Kk expression

Our objective was to determine the relationship between major histocompatibility complex class I molecule expression and the tumorigenic properties of cutaneous neoplasms induced by ultraviolet radiation or chemical carcinogens. All tumors tested were found to express low constitutive levels of MHC class I molecules in vitro as determined by indirect immunofluorescence and flow cytometry. Those tumors capable of growth in UVR-exposed but not in normal recipients (regressors) were found to express enhanced levels of H-2Kk following incubation in the presence of gamma-IFN. In contrast, only one of the tumors that were capable of growth in normal recipients (progressors) exhibited more than moderate enhancement of H-2Kk expression in response to gamma-IFN. Analysis of tumor variants obtained by conversion of a UVR-induced regressor tumor to the progressor phenotype by passage through sublethally gamma-irradiated hosts, or the generation of regressor tumors by mutagen exposure of a benz [A] pyrene (BAP) induced progressor tumor, further supported the direct relationship between tumor immunogenicity in vivo and the capacity to elevate H-2Kk expression in response to gamma-IFN. No correlation existed between H-2Dk expression by the tumors and their transplantation phenotype. Furthermore, we failed to observe MHC class II expression by any of the tumors tested. Finally, the growth rate of a regressor tumor implanted into UVR-exposed hosts was significantly reduced if the tumor was pretreated with gamma-IFN in vitro prior to inoculation. This result suggests that UVR-exposed animals may be deficient in their ability to enhance the expression of MHC class I molecules on developing tumors. This alteration may, in part, account for the state of tumor susceptibility caused by UVR exposure.     

High glucose via peroxynitrite causes tyrosine nitration and inactivation of prostacyclin synthase that is associated with thromboxane/prostaglandin H(2) receptor-mediated apoptosis and adhesion molecule expression in cultured human aortic endothelial cells.

Loss of the modulatory role of the endothelium may be a critical initial factor in the development of diabetic vascular diseases. Exposure of human aortic endothelial cells (HAECs) to high glucose (30 or 44 mmol/l) for 7-10 days significantly increased the release of superoxide anion in response to the calcium ionophore A23187. Nitrate, a breakdown product of peroxynitrite (ONOO(-)), was substantially increased in parallel with a decline in cyclic guanosine monophosphate (GMP). Using immunochemical techniques and high-performance liquid chromatography, an increase in tyrosine nitration of prostacyclin (PGI(2)) synthase (PGIS) associated with a decrease in its activity was found in cells exposed to high glucose. Both the increase in tyrosine nitration and the decrease in PGIS activity were lessened by decreasing either nitric oxide or superoxide anion, suggesting that ONOO(-) was responsible. Furthermore, SQ29548, a thromboxane/prostaglandin (PG) H(2) (TP) receptor antagonist, significantly reduced the increased endothelial cell apoptosis and the expression of soluble intercellular adhesion molecule-1 that occurred in cells exposed to high glucose, without affecting the decrease in PGIS activity. Thus, exposure of HAECs to high glucose increases formation of ONOO(-), which causes tyrosine nitration and inhibition of PGIS. The shunting of arachidonic acid to the PGI(2) precursor PGH(2) or other eicosanoids likely results in TP receptor stimulation. These observations can explain several abnormalities in diabetes, including 1) increased free radicals, 2) decreased bioactivity of NO, 3) PGI(2) deficiency, and 4) increased vasoconstriction, endothelial apoptosis, and inflammation via TP receptor stimulation.     

An experimental study of a new sutureless intraluminal graft with an elastic ring that can attach itself to the vessel wall. A preliminary report

A new sutureless intraluminal graft was developed with an elastic ring made of a flat spring. The diameter of the ring could be reversibly reduced by compression. The sutureless intraluminal graft with an elastic ring can attach itself to the vessel wall by elastic expansion of the ring. The elastic-ring graft was implanted in the descending thoracic aortas of nine dogs and was evaluated histologically and angiographically at different intervals from 18 to 150 days. No complication such as detachment of the ring, aortic rupture, stenosis, or aneurysmal dilatation was observed. With the new graft neither ligation nor posterior aortic wall dissection is necessary, and no anastomotic stenosis occurs. This graft is applicable even if the diameter of the aorta is small. Therefore the elastic-ring sutureless intraluminal graft promises theoretic advantages over sutureless methods that use tape ligation.     

Insulin-dependent diabetes mellitus is associated with genes that map to the right of the class I RT1.A locus of the major histocompatibility complex of the rat

Previous studies have demonstrated that the presence of at least one u-haplotype of the rat major histocompatibility complex (MHC), RT1, is a necessary but not sufficient condition for the development of overt diabetes mellitus. The present studies were undertaken to determine which portion of the RT1 gene complex is necessary for the occurrence of diabetes. We crossed hooded diabetic rats (RT1.AuBuDu) with PVGr8 rats (RT1.AaBuDu). F1 animals were mated to give 82 F2 animals and backcrossed with the hooded diabetics to produce 41 backcross animals. Diabetes occurred in animals with all three possible RT1.A genotypes. The diabetes was similar to that seen in BB rats and in hybrid strains developed from them. An immunoregulatory defect was marked by decreased percentage of peripheral blood lymphocytes staining with w3/25 monoclonal antibody, by an increased percentage of peripheral blood lymphocytes binding a mouse ascites control protein, and by decreased responsiveness of peripheral blood lymphocytes to stimulation by concanavalin A. We conclude that the u-allele of the class I A-locus gene product is not necessary for susceptibility to the development of diabetes in the rat. Therefore, either genes coding for the class II products of the u-haplotype or genes in linkage disequilibrium with these genes and mapping to the right of the A locus provide the permissive condition. Furthermore, the data suggest, but do not prove, that the u-haplotype derived from a strain remote from the BB rat can confer this susceptibility to the development of diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)