Interleukin 2 (IL2) is an important regulator of the immune system. In this report, we have analysed five human melanoma cell lines expressing 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 for the IL2 gene, 72 h after subculture, and the secretion of a biologically active IL2 which specifically sustains the proliferation of the IL2 dependent murine lymphoid cell line CTLL2. In M14 cells, IL2 gene activation is transient as in lymphoid cells but is not inhibited by the 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. Overnight incubation of these cells with polyclonal anti-IL2 antibodies leads to an increased expression of ICAM-1 and a decreased membrane detection of the IL2R alpha, suggesting the existence of an autocrine/paracrine loop involved in the surface expression of these antigens. A decreased expression of the ICAM-1 protein could help some melanoma cells to escape from cytolytic recognition and therefore favour their metastasis.