HLA-DMA and neoplasm: The relevance of tumour cells as APC for CD4+ cells appears to be dependent on the coexpression of MHC II and accessory molecules such as the invariant chain (Ii) and HLA-DM (Armstrong et al, 1997; Brocke et al, 2002), each of which are under the primary control of CIITA, the Class II transactivator.