Declining mitogen-induced polyclonal activity of peripheral blood lymphocytes as an index of immunosuppression involved in different neoplasms]

Regulatory T cells are crucial for maintaining T cell tolerance to-self-antigens and autoimmune process prevention. They are known to be able to cut down in vitro autologous lymphocyte proliferation in mice. It is suggested that their increased levels are responsible for immunosuppression in human tumor growth. Our investigation was concerned with identifying the extent of mitogen-stimulated T- and B-cell concentration changes as well as phenotypic variation in peripheral blood lymphocyte level in lung, stomach, breast and colorectal cancer. It was found that malignancy involves reduced mitogen (PHA, ConA, PWM)-stimulated lymphocyte proliferation and enhanced peripheral blood CD25+-cell concentration which should be accounted for by regulatory T cell increase. However, both the extent of proliferation changes and CD25+-lymphoid cell concentration considerably depended on tumor localization, which might have an indicator of a varying degree of immunosuppression involved in different neoplasms.