HUMAN-MELANOMA CELL-LINE M14 SECRETES A FUNCTIONAL INTERLEUKIN-2

Interleukin 2 (IL2) is an important regulator of the immune system. In this report, we have analysed five human melanoma cell lines expressi ng the IL2R for their ability to secrete IL2. In the M14 melanoma cell line, we observed the appearance of the 0.9 kb transcript specific fo r the IL2 gene, 72 h after subculture, and the secretion of a biologic ally active IL2 which specifically sustains the proliferation of the I L2 dependent murine lymphoid cell tine CTLL2. In M14 cells, IL2 gene a ctivation is transient as in lymphoid cells but is not inhibited by th e immunosuppressive drugs cyclosporine-A and FK506 which are effective on PHA-blasts. In M14 cells, recombinant IL2 (36 pM) induces the down modulation of ICAM-1 expression at the surface of M14 cells. Overnigh t incubation of these cells with polyclonal anti-IL2 antibodies leads to an increased expression of ICAM-1 and a decreased membrane detectio n of the IL2Ralpha, suggesting the existence of an autocrine/paracrine loop involved in the surface expression of these antigens. A decrease d expression of the ICAM-1 protein could help some melanoma cells to e scape from cytolytic recognition and therefore favour their metastasis .