CD4 and neoplasm: Intracellular cytokine staining demonstrated that chTCR-transduced CD4+ T cells mainly reacted to SK37 in comparison with much weaker reactivity by CD8+ T cells, indicating that our MHC-II-restricted tumor-recognizing TCR are largely CD4-dependent, i.e. co-ligation of CD4 with MHC-II is required for full activation of T cells (Fig. 6D).