CD45RC(-) gamma delta(+) T-cell infiltration is associated with immunologic unresponsiveness induced by prior donor-specific blood transfusion in rathepatic allografts

Little is known regarding the role of gamma delta (+) T cells in organ tran splantation. We previously reported that immunologic unresponsiveness is in duced by prior donor-specific blood transfusion (DST) in rat hepatic allogr afts. We investigated the phenotype and distribution of gamma delta (+) T c ells in the hepatic allograft, spleen, and peripheral blood of recipient ra ts with immunologic unresponsiveness induced by DST. gamma delta (+) T cell s were enumerated in allograft livers and spleens by immunostaining and in blood by flow cytometric analysis. The phenotype of gamma delta (+) T cells was determined using CD45RC isoforms derived from alternative mRNA splicin g The cytokine profile of CD45RC(+) and CD45RC(-) gamma delta (+) T cells w as analyzed by reverse transcription polymerase chain reaction. The number of gamma delta (+) T cells in hepatic infiltrates in recipient rats pretrea ted with DST was significantly greater than in untreated animals. This corr elated with significantly higher levels of gamma delta (+) T cell receptor (TCR) mRNA in hepatic allografts of DST-treated rats as compared with untre ated animals. The gamma delta (+) T cell/alpha beta (+) T-cell ratio increa sed in hepatic infiltrates in DST-treated recipient rats but not in untreat ed animals. CD45RC(-)gamma delta (+) T cells were predominantly increased i n DST-treated hepatic allografts compared with untreated allografts, Most o f the intestinal intraepithelial T cells were CD45RC(-)gamma delta (+). Int erleukin (IL)-10 and IL-4 mRNA were detected more in CD45RC(-)gamma delta ( +) T cells than CD45RC(+)gamma delta (+) T cells. CD45RC(-)gamma delta (+) T cells infiltrating liver allografts produce Th2-type cytokines and are as sociated with immunologic unresponsiveness induced by DST.