CD80 and neoplasm: However, even though a study suggested that B7-1 (CD80) positive tumor vaccines may result in some degree of direct antigen presentation to CD8+ T cells (97), in a mouse model, MHC class I-restricted tumor antigens were not detectably presented by the tumor itself (98), thus questioning whether MHC class I expression by SV-BR-1-GM cells indeed contributes to the cell line’s therapeutic potential.