A major corollary of the studies related to the high in vivo immunogenicity of CIITA-driven MHC-II expressing tumors is that MHC class II molecules should be loaded with sufficient quantity of tumor specific peptides, derived from either overexpressed or mutated genes, to generate an efficient functional triggering of tumor-specific CD4+ T cells, an event that we have defined as Adequate Antigen Availability (AAA) (54). The gene discussed is CD4; the disease is neoplasm.