CD8(+)NKR-P1A(+) T cells preferentially accumulate in human liver

A unique subset of T cells that co-express NKR-P1, which is a lectin type o f NK receptor and is thought to have a major role in triggering NK activity , has been identified. In mice, NK1.1 (mouse NKR-P1C)(+) T cells, called NK T cells, preferentially accumulate in the liver and bone marrow. They predo minantly use invariant V alpha 14 chain VCR and phenotypically are CD4(+)CD 8(-) or CD4(-)CD8(-) T cells. In this study, we analyzed, phenotypically an d functionally, the NKR-P1A (analogue of murine NKR-P1C)(+) T cells residen t: in the human liver. Here, we show that in complete contrast to the NKT c ells in the mouse liver, the majority of NKR-P1A(+) T cells in the human li ver are CD8(+) and their TCR repertoire is not skewed to V alpha 24 TCR, th e homologue of murine V alpha 14 TCR. Almost all of the NKR-P1A(+) T cells in the human liver expressed CD69, suggesting that they were activated. Fur thermore, the NKR-P1A(+) T cells in the human liver exhibited strong cytoto xicity against a variety of tumor cell lines including K562, Molt4 and some colonic adenocarcinoma cell lines.