Phenotypic analysis of graft infiltrating cells and major histocompatibility complex expression in actively enhanced rat renal allografts.

In this study donor specific blood transfusion of PVG recipients prevented rejection of DA strain kidneys but, paradoxically, failed to prevent the rapid and progressive accumulation of large numbers of mononuclear cells within enhanced grafts. Morphometric analysis showed that the percentage cellular infiltrate at day 3 was significantly greater in enhanced than in rejecting grafts but a notable feature in the phenotypic analysis of day 5 infiltrates was a markedly reduced number of MRC OX8 positive cells (Tc/s and NK cells) in enhanced grafts. Both rejecting and enhanced allografts showed a marked induction not only of class I but also of class II MHC antigens, and quantitative absorption analysis of donor class I MHC antigens indicated that induction occurred more rapidly in enhanced grafts. Taken together, these findings suggest that blood transfusion sensitizes the recipient, resulting in a more rapid allograft response, but that even in the presence of massive MHC/antigen induction and large numbers of infiltrating cells, immunoregulatory mechanisms are able to suppress the rejection response.