Studies of HLA-DR with relevance to renal transplantation

An Anti-C1s Monoclonal, TNT003, Inhibits Complement Activation Induced by Antibodies Against HLA

Antibody-mediated rejection (AMR) of solid organ transplants (SOT) is characterized by damage triggered by donor-specific antibodies (DSA) binding donor Class I and II HLA (HLA-I and HLA-II) expressed on endothelial cells. While F(ab')2 portions of DSA cause cellular activation and proliferation, Fc regions activate the classical complement cascade, resulting in complement deposition and leukocyte recruitment, both hallmark features of AMR. We characterized the ability of an anti-C1s monoclonal antibody, TNT003, to inhibit HLA antibody (HLA-Ab)-induced complement activation. Complement deposition induced by HLA-Ab was evaluated using novel cell- and bead-based assays. Human aortic endothelial cells (HAEC) were cultured with HLA-Ab and human complement; production of activated complement proteins was measured by flow cytometry. Additionally, C3d deposition was measured on single antigen beads (SAB) mixed with HLA-Ab and human complement. TNT003 inhibited HLA-Ab mediated complement deposition on HAEC in a concentration-dependent manner; C3a, C4a and C5a anaphylatoxin production was also diminished by TNT003. Finally, TNT003 blocked C3d deposition induced by Class I (HLAI-Ab)- and Class II (HLAII-Ab)-specific antibodies on SAB. These data suggest TNT003 may be useful for modulating the effects of DSA, as TNT003 inhibits complement deposition and split product formation generated by HLA-I/II-Ab in vitro.

[Allogenic islet transplantation on the rat liver after allogenic nonparenchymal cells injection in the thymus]

BACKGROUND

[corrected] The major indication for pancreas or islet transplantation is diabetes mellitus type I. This process has to supply the insulin necessity keeping glucose under control

AIM

We studied allogenic islet transplantation on the rat liver, Wistar (RT1u) to Lewis (RT1(1)) as a recipient. Control group (n = 8) and nonparenchymal cell group (n = 8) respectively with injection of Hanks solution and nonparenchymal cells in the thymus before islet transplantation.

MATERIAL AND METHODS

With the method of isolation and purification of the islets we obtained both in the control group 3.637 +/-783,3 islets with purity of 85 +/- 3,52% and nonparenchymal cell group 3.270 +/- 770 islets with purity of 84,25 +/- 2,76%. The nonparenchymal cells were retrieved from the liver and we obtained 2 x 106 cells. Diabetes was induced by i.v. streptozotocin

RESULTS

Control group the transplantation of 3.637 +/- 783,3 islets in the rat liver normalized glucose test, 7,21 +/- 0,57 mmol/L in the 2nd postoperative day. Acute rejection came in the 6th postoperative day with significantly increase of glucose test in nonparenchymal cell group, the transplantation of 3.270 +/- 770 islets in the rat liver, almost normalized the glucose test was 17,95 +/- 5,33 mmol/L in the 2nd postoperative day. From the 4th postoperative day to 10th postoperative day. The glucose test increase significantly showing an early acute rejection

CONCLUSION

The injection of nonparenchymal cells in the thymus before allogenic islet transplantation in the rat liver lead to an early acute rejection.

[Alogenic islet transplantation on the rat liver after alogenic dendritic cells injection in the thymus]

BACKGROUND

The major indication for pancreas or islet transplantation is diabetes mellitus type I. This process has to supply the insulin necessity keeping glucose under control.

AIM

We studied alogenic islet transplantation on the rat liver, Wistar (RT1u) to Lewis (RT1(1)) as a recipient. Control group (n = 8) and dendritic cell group (n = 9) respectively with injection of Hanks solution and dendritic cells in the thymus before islet transplantation.

MATERIAL AND METHODS

With the method of isolation and purification of the islets we obtained both in the control group 3637 +/- 783,3 islets with purity of 85 +/- 3,52% and dendritic cell group 3268 +/- 378 islets with purity of 87 +/- 4,47%. The dendritic cells were retrieved from the spleen and we obtained 3,34 x 105+/-1,16 cells. Diabetes was induced by i.v. streptozotocin.

RESULTS

Control group the transplantation of 3637 +/- 783,3 islets in the rat liver normalized glucose test, 7,21 +/- 0,57 mmol/L in the second post-operative day. Acute rejection came in the 10 postoperative day with significantly increase of glucose test. Dendritic cell group, the transplantation of 3258 +/- 378 islets in the rat liver, normalized the glucose test was 9,3 +/- 2,85 mmoL/L in the second postoperative day. From the 4th postoperative day to 10th postoperative day the glucose test increase significantly showing an early acute rejection.

CONCLUSION

The injection of dendritic cells in the thymus before alogenic islet transplantation in the rat liver lead to an early acute rejection.

The effects of chimeric cells following donor bone marrow infusions as detected by PCR-flow assays in kidney transplant recipients

40 recipients of first cadaver kidney transplants were given perioperative donor vertebral bone marrow infusions (DBMC), compared with 100 controls who did not receive donor bone marrow. The immunosuppressive regimen included OKT3, Tacrolimus, and steroid maintenance therapy, and, in some patients, newly introduced mycophenolate mofetil. This report describes the 24-mo actuarial follow-up and several immunological monitoring studies including sequential measurements of donor bone marrow lineage subset chimerism by the recently reported PCR-flow assay. This is a sensitive in situ PCR detection system for donor versus recipient histocompatibility genes as well as cell surface CD epitope markers using flow cytometry. The results indicate (a) the stabilization of the donor CD3+ and CD34+ cells in recipient peripheral blood at levels below 1% between 6 mo and 1 yr postoperatively, with a 10-fold higher level of donor cell chimerism of these lineages in recipient iliac crest marrow; (b) significantly lower levels of chimerism in peripheral blood up to 6 mo postoperatively in patients who had early acute (reversible) rejection episodes compared with those who did not; (c) a higher degree of chimerism seen in patients who were class II MHC HLA DR identical with their donors; (d) the identification of a high proportion of the donor bone marrow derived CD3 dimly staining subset of T cells (to which regulatory functions have been ascribed) in recipient peripheral blood and especially in recipient bone marrow; and (e) an unexpectedly increased susceptibility to clinically significant infections (primarily viral), and even death in the DBMC-infused group, compared with controls, but no graft losses because of rejection in the DBMC-infused group. Mixed lymphocyte culture assays showed a trend toward a greater number of nonspecifically low reactors in the DBMC group, as well as a greater number of nonspecifically high reactors in the controls (P = 0.058). The autologous mixed lymphocyte reaction also indicated a trend towards nonspecific immune activation in the DBMC group. Finally, anti-cytomegaloviral IgG antibody reactivity was significantly inhibited in the DBMC group 4-6 mo postoperatively (P = < 0.05). In the controls, there were no donor cell lineages detected by PCR-flow in the peripheral blood. These rather unexpected findings, indicating a more depressed cellular and humoral immune capacity in the DBMC cadaver kidney transplant recipients in this relatively early follow-up period, are discussed relevant to chimerism, MHC restriction, and suppressor activity brought about by specialized DBMC subsets, which still need to be defined.

CLINICAL APPLICATION OF FLOW CYTOMETRY IN LIVE RELATED DONOR RENAL TRANSPLANTATION

To monitor the activity of the humoral component in graft dysfunction following renal transplantation using live related donors, flowcytometric cross-match procedure was adopted. Antidonor antibodies were detected in the sera of both pre- and post-transplant patients using conventional serological cytotoxicity cross-match and flowcytometric cross-match assays. In the 52 pretransplant samples no significant differences were observed in flowcytometric and cytotoxicity tests except in 2 secondary transplant cases which were negative by cytotoxicity test. However, in post-transplant samples, floweytometry was found to be a more objective and useful test than cytotoxicity testing in distinguishing 6 out of 7 mild acute-graft-rejection episodes. Both tests were found to be negative in alt 5 cases of cyclosporin-A nephrotoxicity, 7 cases of acute tubular necrosis and 10 out of 11 cases of chronic rejection.

IMPORTANCE OF DONOR SELECTION IN RENAL TRANSPLANTATION

Renal transplantation has become a treatment of choice for patients with end stage renal disease. A successful transplant is the result of a combination of several factors acting synergistically, such as the degree of HLA compatibility between donor and the recipient, pretransplant blood transfusions, the recipient's state of immunoreactivity and sensitization, immunosuppressive therapy given in post operative period etc. Donor selection appears to be the most critical factor for the long term success of the organ graft. In this brief review, some of the important parameters of donor selection in renal transplantation are highlighted.

Human ciliated bronchial epithelial cells: expression of the HLA-DR antigens and of the HLA-DR alpha gene, modulation of the HLA-DR antigens by gamma-interferon and antigen-presenting function in the mixed leukocyte reaction

HLA-DR class II molecules are expressed by a variety of nonlymphoid cells, including the respiratory epithelium. However, it is not known if ciliated bronchial epithelial cells express the HLA-DR genes, if the expression of class II molecules on their surface can be modulated by immune mediators and, finally, if these cells, like other HLA-DR-positive epithelial cells, have the potential to serve as antigen-presenting cells. To answer these questions, we collected ciliated bronchial epithelial cells by brushing and by suction during fiberoptic bronchoscopy and by scraping surgically resected bronchi. The number of cells recovered by brushing or suction during fiberoptic bronchoscopy was similar (P greater than 0.2), but lower than that obtained by scraping surgically resected bronchi (P less than 0.01); however, compared with brushing, suction of ciliated bronchial epithelial cells resulted in a better viability (P less than 0.05). HLA-DR antigens on ciliated bronchial epithelial cells were detected by immunofluorescence using the PTF 29.12 and the L243 monoclonal antibodies, both recognizing HLA-DR molecules on the vast majority of ciliated bronchial epithelial cells. Cytoplasmic dot blot analysis demonstrated that ciliated bronchial epithelial cells had mRNA HLA-DR transcripts, and Northern blot hybridizations showed that the size of the HLA-DR messages was the same observed in other HLA-DR-positive cells. Interestingly, ciliated bronchial epithelial cells showed a significant decline of HLA-DR expression after 5 days in culture, but the addition of gamma-interferon to the cell cultures was associated with the persistence of the expression of class II antigens on the cell surface (P less than 0.01 with control cultures at 5 days). Finally, while ciliated bronchial epithelial cells were ineffective in stimulating allogeneic T cell proliferation in a 6-day primary mixed leukocyte reaction (MLR), the addition of phorbol myristate acetate to the MLR was able to induce a significant T cell proliferation (P less than 0.001, all comparisons). Thus, human ciliated bronchial epithelial cells express HLA-DR surface antigens and have mRNA molecules for the HLA-DR genes, and the expression of the surface class II antigens can be modulated in vitro by immune mediators.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood transfusion in renal transplantation--the induction of tolerance by incompatibility for class I antigen

Blood transfusion given before renal transplantation has been shown to have a powerful immune modulating effect on recipient response to kidney allograft. The mechanism responsible for this effect is still unknown. Here it is assumed that, due to incompatibility for HLA-A related class I antigens between blood donor and recipient, pretransplant blood transfusion may allospecifically induce in the recipient the generation of T cells that have a suppressive effect on T lymphocyte response to incompatible HLA class II antigens present on kidney allograft. Although in many respects this interpretation is still speculative, it is in accord with findings reported from clinical and experimental studies of the effect on graft survival of blood transfusion, both random and donor specific.

Implication of structural class II gene polymorphism for the concept of serologic specificities

We have used DNA-DNA hybridization methods to study the relationship of genetic polymorphisms to the established HLA-D region determinants as detected with serological reagents. The supertypic determinants DRw52 and 53 are closely associated with a particular RFLP detected with the DR beta probe, but are seemingly encoded by a distinct beta gene compared to the "conventional" DR antigens. DQw1 is closely associated with a DQ alpha chain polymorphism, whereas the DQw2 and 3 specificities have correlations to RFLP using the DQ beta probe. Additional DQ polymorphism, in linkage disequilibrium with DR but yet without a serological counterpart is also described. Considering the finding that there exist a varying number of DR beta genes in different DR haplotypes (Böhme et al. 1985), from 1 in DRw8 to 3 (or 4) in DR4- and DR7-positive cells, we have made a tentative re-evaluation of the genetic basis for the conventional DR specificities. The combination of cell surface antigens encoded by DR and DQ loci are believed to form the basis for MLC stimulating determinants. We have speculated that a combination of determinants encoded by distinct DR beta genes and in certain instances additional DQ polymorphism is responsible for the DR types. Thus, only a limited variability is observed after DNA-DNA hybridization using DR beta probes. Only DR1-, 2- and 4-positive cells have distinct bands not detected in any other haplotypes, whereas DR3, 5, w6, and w8 can be characterized by a combination of bands, which is the result of hybridization with several DR beta genes. Furthermore, we have suggested that the difference between the DR3 and DRw6 specificities is due to variability with regard to 1 DQ beta gene, and have also made the assumption that DRw6 cells may express a lower concentration of DR locus encoded products compared to DR3-positive cells (Haziot et al. 1985). In addition, we have discussed the genetic basis for so-called DR blanks, implying that an unorthodox combination of DR and DQ determinants forms the basis for difficulties in assigning DR types to such cells in some cases and that "blanks" can be associated with low expression at the cell surface of well-known DR determinants. The use of cDNA and genomic probes for distinct class II genes to elucidate the mechanisms of HLA and disease association has been documented and discussed.

RISH III. Haplotype-sharing in immune responses

A number of hypotheses have been proposed for the reactivity of lymphocytes with allogeneic tissue. However, these hypotheses have not been generally accepted for they cannot accommodate the observation that lymphocytes from chimeras cooperate with each other. Also, only a few percent of lymphocytes react with allogeneic tissue in rejection reactions.

Characterisation of renal antigens on distinct parts of the human nephron by monoclonal antibodies

Ten monoclonal antibodies (TN 1-TN 10) directed against different renal antigens of distinct sites of the human nephron were derived from a fusion between P3-NS1/1-Ag4-1 mouse myeloma and spleen cells of a mouse hyperimmunized against isolated human kidney cells. Two of these reagents (TN 1, TN 10) were shown by immunoperoxidase labelling on frozen sections of five normal kidneys and of other selected human organs, as well as by immunofluorescence studies on normal peripheral blood cells and selected lymphohematopoietic cell lines, to detect antigens exclusively expressed on visceral glomerular or proximal tubular epithelial cells. The other eight antibodies were found to react with different determinants shared between renal structures, muscle cells, different epithelia, B-lymphocytes and granulocytes. In heterogeneous cultures of isolated kidney cells these monoclonal reagents could be used to identify distinct cell types of tubular origin. Thus such hybridoma-derived antibodies provide new tools to correlate structural characteristics of various renal epithelial cells with their functional properties and will contribute to the study of their influence on immunologically mediated kidney injuries in different forms of glomerulonephritis in man.