CD4 and neoplasm: Although some solid-tumor cells do express either constitutive or inducible MHC-II, our results indicate that despite the presence of oncogene-specific CD4+ T cells among TILs and PBMCs, these cells cannot directly recognize and lyse antigen-expressing MHC-II+ tumor cells, whereas epitopes from the same protein may be effectively presented to CD8+ T cells on MHC-I (13).