The expression of intercellular adhesion molecule-1 (ICAM-1) in mouse B16 and human melanoma cell lines was investigated by indirect immunofluorescence using a FACScan analyzer. Mouse B16 melanoma cell lines (B16-F1 and F10) did not express ICAM-1 under ordinary culture conditions. Neither in vitro hyperthermia at 41 degrees C for 3 or 6 hr nor cytokines such as gamma interferon (IFN-gamma) or tumor necrosis factor alpha (TNF-alpha) induced ICAM-1 expression in B16 melanoma cell lines. A combination of IFN-gamma with TNF-alpha caused slight induction of ICAM-1 expression in the B16-F10 melanoma cell line. Hyperthermia at 41 degrees C for 3 hr in combination with the cytokines induced a slight expression of ICAM-1 in the B16-F1 melanoma cell line. Hyperthermia at 41 degrees C for 3 hr or 6 hr did not induce de novo ICAM-1 expression but hyperthermia at 43 degrees C for 6 hr caused rather suppression of the expression of ICAM-1 in the three human melanoma cell lines tested. In contrast, they showed a clear increase in the expression of ICAM-1 after treatment with either with IFN-gamma or TNF-alpha, and the expression was further augmented by a combination of the two cytokines. Treatment with cytokines in combination with hyperthermia at 41 degrees C or 43 degrees C for 3 hr did not augment the expression of ICAM-1 over that in cytokine-treated human melanoma cell lines, at normal temperatures. Thus, it is concluded that mouse B16-F1 and F10 melanoma cell lines are different from human melanoma cell lines in terms of induction of ICAM-1 expression by cytokines and/or hyperthermia.