Serological identification and bioinformatics analysis of immunogenic antigens in osteosarcoma

In order to improve disease-free survival and potentially a cure, it is necessary to identify more potent osteosarcoma antigen. Here, we defined the osteosarcoma-associated antigen (OSAA) recognized by the humoral immune system for the first time. We have applied the method of serologic analysis of recombinant cDNA expression library (SEREX) on osteosarcoma, followed by DNA sequencing and analyzing of positive clones. Then, the reactivity of normal and other bone tumor sera with positive clones were performed. Seven distinct novel antigens reactive with IgG antibodies were identified by SEREX analysis on osteosarcoma patients and were characterized according to cDNA sequence and the reactivity with allogeneic sera. Five of the seven antigens identified in this study were recognized by IgG antibodies in normal sera, and the remaining two were recognized exclusively by sera from allogeneic osteosarcoma patients but not by normal donor sera, suggested that the immune response to the two antigens are osteosarcoma related. Crude lysate ELISA methodology indicated that the optical density value of OSAA-3 and OSAA-5 were significantly higher in OS patients than in healthy donors. The two immunogenic antigens detected by immune responses might facilitate the identification of epitopes recognized by antigen-specific cytotoxic T lymphocytes (CTL). In summary, the antigens identified in this study may be potential candidates for diagnosis and targets for immunotherapy in osteosarcoma (OS).