Of the two tumor-specific T lymphocyte subsets, CD8+ cytotoxic T lymphocytes (CTL) recognize tumor-associated antigen (TAA)-derived peptides in the context of MHC class I molecules (MHC-I), whereas CD4+ helper T (Th) cells respond to peptide-MHC class II (MHC-II) complexes. This evidence concerns the gene CD4 and neoplasm.