Augmentation of IgM antibody to gp43 tumor-associated antigen peptide by melanoma cell vaccine

We previously reported that gp43 tumor-associated antigen peptide (DLTMKYQIF; designated 810 antigen) on human melanoma cells is recognized by IgM human monoclonal antibody L92 and by cytotoxic T lymphocytes (CTL). In this study, we retrospectively tested sera of 44 patients with regional metastatic melanoma (22 who recurred within 1 year and 22 who survived longer than 5 years) to determine if antibody responses to 810 antigen could be induced by immunization with an allogeneic melanoma cell vaccine that contained 810 peptide. IgM and IgG antibodies were assessed by enzyme-linked immunosorbent assay using a synthetic 810 nonamer peptide. A significant augmentation of IgM antibody was demonstrated 4 weeks after initiation of vaccine therapy, and the IgM level was significantly higher in patients who survived more than 5 years. The antigen epitope recognized by antibodies was located within TMKYQI. Of this epitope sequence, K appears to play a central role in antigenicity. The 810 antigen recognized by antibody and CTL may have clinical relevance as a potential source of melanoma vaccine.