The role of HLA matching in renal transplantation

Humanized Mouse Model as a Novel Approach in the Assessment of Human Allogeneic Responses in Organ Transplantation

The outcome of organ transplantation is largely dictated by selection of a well-matched donor, which results in less chance of graft rejection. An allogeneic immune response is the main immunological barrier for successful organ transplantation. Donor and recipient human leukocyte antigen (HLA) mismatching diminishes outcomes after solid organ transplantation. The current evaluation of HLA incompatibility does not provide information on the immunogenicity of individual HLA mismatches and impact of non-HLA-related alloantigens, especially in vivo. Here we demonstrate a new method for analysis of alloimmune responsiveness between donor and recipient in vivo by introducing a humanized mouse model. Using molecular, cellular, and genomic analyses, we demonstrated that a recipient's personalized humanized mouse provided the most sensitive assessment of allogeneic responsiveness to potential donors. In our study, HLA typing provided a better recipient-donor match for one donor among two related donors. In contrast, assessment of an allogeneic response by mixed lymphocyte reaction (MLR) was indistinguishable between these donors. We determined that, in the recipient's humanized mouse model, the donor selected by HLA typing induced the strongest allogeneic response with markedly increased allograft rejection markers, including activated cytotoxic Granzyme B-expressing CD8+ T cells. Moreover, the same donor induced stronger upregulation of genes involved in the allograft rejection pathway as determined by transcriptome analysis of isolated human CD45+cells. Thus, the humanized mouse model determined the lowest degree of recipient-donor alloimmune response, allowing for better selection of donor and minimized immunological risk of allograft rejection in organ transplantation. In addition, this approach could be used to evaluate the level of alloresponse in allogeneic cell-based therapies that include cell products derived from pluripotent embryonic stem cells or adult stem cells, both undifferentiated and differentiated, all of which will produce allogeneic immune responses.

HLA mismatching and cytomegalovirus infection as risk factors for transplant failure in cyclosporin-treated renal allograft recipients

In a study of the effects on renal allograft survival of HLA mismatching, mismatching for cytomegalovirus (CMV) antibody status, and post-transplant CMV infection, 148 cyclosporin-treated renal transplant recipients were given kidneys optimally matched for HLA-A, -B, and -DR antigens but not matched for CMV antibody status. Mismatching for HLA-B and -DR antigens was associated with a greater number of rejection episodes and a lower graft survival, but mismatching for CMV antibody status and posttransplant primary or recurrent CMV infection exerted no effect on graft survival. The role of matching of renal transplant recipients and donors for CMV antibody status in preference to HLA matching (proposed as a means of reducing the mortality associated with primary CMV infection) is discussed.

An interactive computer program for the analysis of HLA class II restriction fragment patterns

There is considerable current interest in the application of Southern blotting and hybridization, with locus-specific HLA class II probes, to HLA typing. The work of several laboratories has shown that, under suitable conditions, restriction fragment patterns that correlate with DR and DQ serology and with DP cellular reactivities can be obtained from homozygous cell lines. Although the identification of class II specificities from restriction fragment patterns is relatively straightforward in homozygotes, the increased complexity of the patterns obtained from heterozygotes makes the interpretation considerably more difficult; this difficulty is compounded by even slight variation between and within gels. We have developed an interactive computer program that allows HLA-DR and DQ typing by the visual matching of restriction fragment pattern data with standard data derived from a panel of well-characterized homozygous cell lines. The program also uses a simple algorithm (after Southern) to estimate the fragment sizes in the unknown track. The screen display can be printed out to give a convenient record of the match; a numerical measure is also given of the goodness of fit of the new data.

The role of H-2 and non-H-2 antigens and genes in the rejection of murine cardiac allografts

Genes of the major histocompatibility complex (MHC) in the mouse (H-2 complex) have been shown to be an important factor in determining the immune responsiveness of various strains of mice to isolated antigens (e.g., lysozyme). The role of MHC genes in controlling the responsiveness of mice to multiple alloantigens is less well-defined, and although non-MHC genes have been shown to be important in determining responsiveness in some systems (e.g., haptens), they have not been demonstrated as yet to influence the rejection of vascularized organ allografts. In this study, the responsiveness of mice to vascularized cardiac allografts transplanted across well-defined major (H-2) and minor (non-H-2) histocompatibility barriers was investigated using congenic mice in 32 different donor/recipient combinations. The results show that both H-2 and non H-2 gene products can act as target alloantigens for rejection. At the responder level, they may interact to effect responsiveness of a recipient strain to multiple alloantigens. In no case in this study has any one gene or group of genes been found to confer universal high or low responder status.