A chemical carcinogen, 3-methylcholanthrene, alters T-cell function and induces T-suppressor cells in a mouse model system.

The in-vivo effects of a polycyclic aromatic hydrocarbon (PAH), 3-methylcholanthrene (MCA), on in-vitro mitogen activation, cell-mediated lympholysis (CML) and T-cell subset distribution in mouse splenic lymphocyte populations were measured. Three inbred mouse strains were treated with a single intraperitoneal injection of corn oil alone or with different doses of MCA in oil (0.5-50 mg kg -1). One to ninety days after injection, splenic lymphocytes were isolated, and assayed for blastogenesis, CML and the percent T-helper and T-suppressor cells using monoclonal antibodies. High doses of MCA suppressed mitogen activation (15.2-53.6%) and CML (69-90%) within 24 hr in lymphocytes from PAH-responsive mice (C57 and C3H). Blastogenesis was stimulated and CML was suppressed to a lesser degree (5-45%) in lymphocytes from non-responsive mice (DBA). MCA induced an increase in T-suppressor cells in responsive mice, but there was no change in DBA mice. These studies suggest a correlation between immunocytotoxicity of PAH compounds on T-cell subsets and the responsiveness of mouse strains to these carcinogens.