Whilst CTLs can directly recognise and kill tumour cells, provided they express MHC class I molecules, CD4+ T cells provide help, but also contribute directly to tumour eradication via direct cytotoxic effects, induction of senescence, or indirect IFN-γ-mediated potentiation of tumouricidal macrophages and inhibition of angiogenesis [4]. This evidence concerns the gene CD4 and neoplasm.