We examined the role of cell adhesion molecules (CAM) by which tumor cells bind to the endothelial cells using human umbilical vein endothelial cells (HUVEC) and cultured melanoma cells. Endothelial cells from human umbilical veins were isolated and examined for CAM expression and its modulation by tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), interleukin-6 (IL-6) or interferon-gamma (IFN-gamma). The expression of intercellular adhesion molecule 1 (ICAM-1) on HUVEC was increased by TNF-alpha, IL-1 and IFN-gamma when measured by ELISA or flow cytometric (FACS) analysis. IL-6 did not increase ICAM-1 expression on HUVEC. Two melanoma cell lines, Malme-3M and SK-Mel-28, showed increased expression of ICAM-1 after treatment with TNF-alpha, IL-1 and IFN-gamma in FACS analysis. IFN-gamma induced increased expression of HLA-DR only in SK-Mel-28 melanoma cells, not in Malme-3M melanoma cells. Neither HUVEC nor melanoma cells expressed lymphocyte function-associated antigen 1 (LFA-1) in either the basal (i.e., cytokine untreated) condition or the cytokine treated condition. Melanoma cells showed minimal increment in adhesion to TNF-alpha or IL-1 treated HUVEC than to cytokine untreated HUVEC. HUVEC and melanoma cells did not express LFA-1 and increased ICAM-1 expression by TNF-alpha, IL-1 and IFN-gamma treatment in FACS analysis did not coincide with minimal increase of melanoma cells adhesion to cytokine treated HUVEC. These results suggest that adhesion between melanoma cells and HUVEC is probably mediated by molecular interaction other than ICAM-1/LFA-1.