Increase in the proportion of granulated CD56+ T cells in patients with malignancy

Abstract

Evidence is presented for the existence of a unique T cell population which expressed one of the natural killer (NK) markers, CD56 antigen, in humans. Although such 0056⁺ T cells were a minor population in the peripheral blood (< 10%). They were abundant in the liver (up to 50%). which was recently demonstrated to be a major organ for extrathymic T cell differentiation in mice. As in the case of extrathymic T cells in mice, these CD56⁺ T cells in humans contained a higher proportion of γδ cells than did CD56⁻ T cells, contained double-negative CD4⁻⁸ cells, and had the morphology of large granular lymphocytes. This unique population of CD56⁺ T cells tended to be elevated in the blood and among tumour-infiltrating lymphocytes in patients with colorectal cancer, especially in advanced cases. These results raise the possibility that, as in mice, CD56⁺ T cells with extrathymic T cell properties may also be associated with tumour immunity in humans.