The fact that CD4+ T cells colonized CIITA-tumor tissue before CD8+ T cells and DC, along with the capacity of CIITA-expressing tumor cells to process and present antigenic peptides to CD4+ T cells in vitro [32,35], supports the hypothesis that much of the tumor-specific TH cell triggering and/or restimulation takes place in the tumor tissue itself and is directly mediated by tumor cell-derived MHC class II molecules, as previously suggested [36-38]. The gene discussed is CD4; the disease is neoplasm.