EXPRESSION OF THE COSTIMULATORY MOLECULE CD40 ON MELANOMA-CELLS

We have previously shown that one of the co-factors required for gener ation of T-cell responses, B7.1, is variably expressed on melanoma cel ls. In the present studies we have examined the expression of another important co-factor in T-cell responses, viz., CD40, and investigated regulation of its expression and possible function(s). PCR analysis re vealed mRNA for CD40 in alt 18 cell lines established from metastatic melanoma and the majority of those from 6 primary melanoma. CD40 prote in was detectable in approximately 50% of the cell lines by now cytome try and in sections from only 2 of 20 melanoma. Expression of CD40 pro tein was increased in 2 of 3 cell lines with constitutive CD40 express ion by interferon-gamma but not by granulocyte/macrophage colony-stimu lating factor, interleukin-2 or tumor necrosis factor-alpha. Interacti on of monoclonal antibody with CD40 on melanoma cells resulted in an i ncrease in their cell division but did not increase expression of the co-stimulatory factor B7. Our results suggest that CD40 expression on melanoma may have important effects on their biology. The influence of CD40 expression on T-cell responses to melanoma remains to be investi gated. (C) 1996 Wiley-Liss, Inc.