EXPRESSION OF IL-2 RECEPTORS IN HUMAN-MELANOMA CELLS

Melanoma cells can secrete several cytokines and express various cell surface molecules, such as the intercellular adhesion molecule ICAM-1, class II histocompatibility antigens, and the CALLA antigen, typicall y found in cells of the immune system. We have investigated the possib le expression of interleukin-2 (IL-2) receptors in melanoma using mono clonal antibodies specific for the p55/alpha chain (TAC antigen) and t he p75/beta subunit. Flow cytometric analysis of cultured melanoma cel ls showed the presence of low levels of the TAC antigen and of the bet a chain on the surface of several cell lines. Similar results were obt ained in vivo by immunohistochemistry on cryosections prepared from cu taneous and ocular melanoma explants. Positive staining was observed f or the a chain of the IL-2 receptor in a high percentage of tumour cel ls. The beta chain could also be detected, although in a limited numbe r of specimens. Analysis of RNA from melanoma cell lines by Northern b lot showed the presence of typical 4 Kb transcripts for the p75 subuni t, while low-abundance message for the p55 chain could be detected usi ng combined reverse transcription/polymerase chain reaction analysis. Together, these results suggest that melanoma cells may express high a ffinity receptors for IL-2.