Scenario 3. A partially activated CD4+ T cell with no self-reactivity may become a clone of helper T cells that will mediate autoimmunity or anticancer immunity. For a partially activated CD4+ T cell which does not cross-react with any of the self-peptides presented by mTECs, there are a few possibilities: i. This peptide may come from a transformed or cancer cell. This evidence concerns the gene CD4 and cancer.