EXPRESSION OF AMINOPEPTIDASE N CD13 IN TUMOR-INFILTRATING LYMPHOCYTESFROM HUMAN RENAL-CELL CARCINOMA/

We have previously demonstrated the expression of aminopeptidase N (AP N, CD13) on synovial T cells from patients with different forms of art hritis. T cells of peripheral blood and serous body fluids are CD13-ne gative but can be stimulated to express CD13 after activation, e.g., w ith Con A. In the present report, double-labelling and flow cytometry analyses were performed to characterize the phenotype of tumour-infilt rating lymphocytes (TIL). A large panel of antibodies specific for dif ferent activation-associated molecules on T cells was used. In contras t to TIL of lung cancer, TIL of renal cell carcinoma (RCC) consisted o f significantly higher percentages of T cells expressing CD13, dipepti dylpeptidase N (DPIV, CD26) and HLA-DR, whereas T cells of lung cancer expressed more CD25, CD69 and CD54/ ICAM1. No differences could be fo und in the expression of CD45RO, CD49a/VLA-1 and CD62L/L- selectin. Ou r results demonstrate that T cells in RCC and lung cancer differ in th eir phenotype, especially with respect to surface aminopeptidases. Inv estigations into the function of APN on T cells could be of help in ga ining deeper insight into tumour defence as well as into general mecha nisms of T cell functions.