Human melanoma cells express a functional interleukin‐2 receptor

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Abstract
Flow cytometric analysis reveals that 5 human melanoma cell lines (M14, IGR3, MEI 477, JUSO, GLL 19) 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 (M 14, IGR3, ME 1477). 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 MI4 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, 10TI4) 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.

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