Examples of CD4 T-cell responses to TAA expressed by solid tumors. HTL clones specific for HER2/neu883–899 (A), CEA653–667 (B), PSMA334–348 (C), TARP14–27(D), and WT1124–138-reactive (E) were shown recognize naturally processed antigens derived from recombinant protein or a cell lysate from the prostate tumor LNCaP presented by DCs in the context of MHC-II molecules. A gp100175–189-reactive CD4 HTL clone (F) directly recognizes peptide presented by autologous EBV-LCL and an MHC-II+, gp100+ melanoma tumor mel697 but not the gp100 negative EBV-LCL This recognition is inhibited by anti-HLA-DR antibodies (αDR). MAGE-A3146–160-reactive (G) CD4 HTL clone recognizes directly MHC-II expressing, MAGE-A3+ (HT144 and 624mel) melanomas and react with recombinant MAGE-A3 protein presented by autologous PBMC. STEAP102–116-reactive HTL (H) recognizes peptide or cell lysate from STEAP+ (LNCaP) tumor cells. In addition, this HTL can recognize directly a STEAP+, DR+ prostate tumor cell line (PC3).