The immune system, apoptosis and apoptosis-related proteins in human ovarian tumors (A review)

Our studies on the relationships among the lymphoid system, apoptosis and a poptosis-related proteins (ARP) in human ovarian benign cysts, borderline t umors, and carcinomas are reviewed and analyzed. Fas and Fas ligand are exp ressed in 50% to 80% of the epithelial cells in all studied tumors. Many bc l-2-positive tumor epithelial cells are seen in benign cysts and they disap pear as tumorigenesis progresses, whereas p53 protein is found only in bord erline tumors and in carcinomas. Many exceptions to the opinion that bcl-2 inhibits apoptosis and p53 promotes it are encountered. Bcl-2 is lacking in epithelial cells of mucoid tumors of all grades, and its absence does not stimulate their apoptosis. P53 protein is absent from most lymphocytes, mac rophages and epithelial tumor cells, nevertheless, they undergo apoptosis. Indeed, in many tumors apoptosis is regulated without the participation of bcl-2 and p53. Different components of the immune system become active duri ng different stages of tumor development. The weak reaction of T-cell kille rs and macrophages is typical in benign cysts. In borderline tumors, the ac tivity of T-cell killers increases in the parenchyma, and that of T helpers and macrophages in the stroma. In carcinomas with high lymphoid infiltrati on, a strong reaction of macrophages and T cell killers in the tumoral pare nchyma as well high reaction of T helpers and B lymphocytes in the stroma a re typical. Apoptosis that should protect against tumor also stimulates apo ptotic death of lymphocytes and macrophages, and this has catastrophic cons equences, as seen in weakly infiltrated carcinomas. In conclusion, our stud ies indicate that during malignancy the major task of the immune system is curtailment and control of tumorigenesis.