T-CELL RECEPTOR-ALPHA AND BETA-CHAIN GENE-EXPRESSION IN CELLS INFILTRATING HUMAN CARDIAC ALLOGRAFTS

Intragraft T-cell receptor (TCR) ct and beta chain variable region gen e expression was analyzed in human cardiac allograft biopsies by rever se transcription polymerase chain reaction, Rearranged TCR alpha and b eta chain gene transcripts were detected in all biopsies examined (N = 23), indicating the presence of T cells bearing the alpha/beta TCR ev en in the absence of microscopically apparent leukocyte infiltration. In this analysis, a broad TCR alpha/beta repertoire in actively reject ing lesions was demonstrated, whereas fewer TCR alpha and beta chain g ene families were detected in nonrejecting lesions. The number of expr essed TCR VP chain gene families typically was two-to sixfold higher t han that of V alpha chain families in all biopsies tested. This asymme tric relation was present throughout the histologic grading spectrum o f the biopsies. Based on these data, the TCR repertoire is heterogenou s even in the early stages of mononuclear cell infiltration of the all ograft. Also based on the data, the presence of T cells in grafts with minimal cellular infiltrates is not a specific marker of subsequent r ejection episode, because T cells were identified in all allograft bio psies.