Characterization of human cardiac infiltrating cells post transplantation. 1. Phenotypic and functional alloreactivity.

Sequential cardiac biopsies from patients post transplantation were studied for histological evidence of grades of rejection, the immunophenotype of the mononuclear cell infiltrate if present and, in addition, aliquots of the same biopsy were cultured in vitro with medium containing interleukin-2. The exuding mononuclear cells were expanded and bulk cultures and T cell lines resulting from this were evaluated phenotypically and functionally for donor specific alloreactivity. Results of these studies demonstrate: (1) No strict correlation of histological rejection grades with immunophenotype or degree of mononuclear cell infiltrate. (2) The mononuclear cell cultured from 102 biopsies yielded 47 relatively pure CD4+ T cell cultures and 12 cultures enriched for CD4+ T cells, 16 relatively pure CD8+ T cell cultures and 15 cultures enriched for CD8+ T cells, 7 cultures which consisted of dual marked CD4+ CD8+ T cells and 5 which were negative for both CD4 and CD8 but expressed CD3. (3) Of the 59 total CD4+ T cells, 6 demonstrated donor specific CTL reactivity and of the 31 CD8+ T cells, 26 demonstrated donor specific CTL activity. (4) None of the CD4+ CD8+ T cell cultures demonstrated CTL reactivity and all 5 of the CD3+ CD4- CD8- T cell cultures demonstrated potent donor specific CTL activity. (5) Of the 102 cultures, 89 showed donor specific PLT function. (6) High MHC-Class I expression by cardiac myocytes correlated with high frequency of CTL cultures. These data provide a summary of the phenotype and functional analysis of T cells in cardiac biopsy specimens and provide valuable reagents for further studies on the mechanisms involved in human cardiac allograft rejection.