Naïve CD4+ T cells purified from healthy donors and preactivated with anti-CD3 antibody were co-cultured with different types of tumor cell lines, including breast cancer (MCF7), melanoma (M586 and M628), colon cancer (SW480 and CC2), ovarian cancer (OC155), prostate cancer (DU145 and PC3), and squamous cancers (SSC25 and CAL27), or with normal breast cells (BN2 and BN5). This evidence concerns the gene CD4 and prostate cancer.