Human melanoma cells with high susceptibility to cell-mediated lysis can be identified on the basis of ICAM-1 phenotype, VLA profile and invasive ability.

Marked heterogeneity for susceptibility to lysis by autologous CTL clones and allogeneic IL-2-activated CD3- and CD3+ lymphocytes was found among 19 clones isolated from a human metastatic melanoma (Me665/2). A subset of 5 clones with the highest susceptibility to lysis had increased ICAM-1 antigen expression. Phenotype analysis for the presence of extracellular matrix receptors in the beta 1- and beta 3-integrin families revealed that the tumor clones with the highest susceptibility to lysis were also characterized by frequent expression or increased expression of multiple receptors in the beta 1 family including VLA-1, -2, -3, -4 and -6. The correlation between phenotypic markers and susceptibility to lysis, seen at the clonal level, was confirmed by selection experiments on the uncloned metastasis Me665/2. In fact, the neoplastic population surviving 3 cycles of immunoselection with IL-2-activated lymphocytes exhibited, in comparison to the unselected metastasis: (1) reduced susceptibility to lysis and (2) reduced expression of ICAM-1 and of VLA antigens. In contrast, enhanced susceptibility to lysis and up-regulation of ICAM-1, VLA-1 and VLA-3 antigens were observed on melanoma cells recovered after invading a reconstituted basement membrane. These data indicate that melanoma cells with enhanced susceptibility to cell-mediated lysis can be identified on the basis of phenotypic characteristics (ICAM-1 and VLA antigen profile) and functional features (invasive ability on reconstituted basement membranes).