Human melanoma cells express a functional interleukin-2 receptor

Flow cytometric analysis reveals that 5 human melanoma cell lines (M14, IGR3, ME1477, JUSO, GLL19) express both α and β chain of the interleukin 2 receptor (IL-2Rα and IL-2Rβ). These chains are able to specifically bind IL-2 and to form high-affinity heterodimers (IL-2Rαβ). Analysis of poly A⁺ RNAs by Northern blot reveals the presence of typical transcripts for both the IL-2Rα gene (3.6 kb) and the IL-2Rβ gene (4 kb). Reverse transcription/polymerase chain reaction analysis allowed transcripts for the IL-2Rγ (p64) gene to be detected in 3 of these melanoma cell lines (M14, IGR3, ME1477). Incubation with human recombinant IL-2 modifies in IL-2Rα⁺β⁺γ⁺ (M14) the expression of several surface molecules: down-regulation of ICAM-1, HLA class I and HLA-DR and up-regulation of CD44. IL-2 is also active on IL-2α⁺β⁺γ^- cell lines since it decreases ICAM-1 and HLA class-II expression at the surface of JUSO cells. Down-regulation of ICAM-1, whose expression in melanoma cells is a marker of tumor progression, is detectable within 3 hr in M14 cells and is maximal after 48 hr incubation, at IL-2 concentrations corresponding to the high-affinity heterodimers. This feature is specific since it is partially inhibited by MAbs directed against the IL-2 binding site of the IL-2Rα (MAR93, I0T14) and IL-2Rβ (MiKβ1, TU27) chains. Our data support the notion of a direct effect of IL-2 on human melanoma cells. Modulation of the expression of surface molecules which is important for the interaction with immunocompetent cells or for tumor progression, could have a role to play during in vivo IL-2 treatment of human melanomas.