CD4 and neoplasm: To elucidate how OT-II recognition of B16-OVA tumor cells was occurring, given that most tumors do not constitutively express MHC II, we monitored MHC II expression on live B16-OVA cells after coculture with S1 + S2 aAPC-activated OT-II cells, finding that the CD4+ T cells induce MHC II expression on B16-OVA in an IFN-γ dependent manner (Fig. 3f and Supplementary Fig. 4h).