HLA-C and neoplasm: That direct presentation could be a component of tumor immunity is suggested by: 1) the reported demonstration of direct presentation in viral and other tumor model systems [7,29]; 2) the effectiveness of tumor vaccines established by transfecting tumor cells with MHC and costimulatory genes [30]; and 3) the conversion of tumor cells to APCs by epigenetic agents discussed above and previously reported [14,18].