Subclinical effects of groundwater contaminants. I: Alteration of humoral and cellular immunity by benzene in CD-1 mice.

Abstract

Benzene is a known contaminant found in trace amounts in ground water. It has long been associated with myelotoxicity and associated immunologic effects. The present study concerned the immunotoxic potential of benzene following four weeks of continuous oral administration via drinking water at concentrations of 0, 31, 166 and 790 mg/L. Benzene-treated water produced a dose-related decrease in spleen weight and increase in kidney weight; both were significantly different at the highest level. Benzene exposure caused a significant dose-response reduction of peripheral blood leukocytes, lymphocytes, erythrocytes and resulted in a severe macrocytic anemia. Splenic lymphocyte proliferation to both B cell and T cell mitogens [lipopolysaccharide (LPS), pokeweed mitogen (PWM), concanavalin A (Con A) and phytohemagglutinin (PHA)] was followed by a dose-related biphasic responsiveness, enhanced at the lowest dose (31 mg/L) and depressed in the higher dosage groups (166 and 790 mg/L). Cell-mediated immunity as measured by mixed-lymphocyte culture (MLC) response to allogeneic cells and cytotoxic T lymphocyte (CTL) activity to YAC-1 tumor ceils exhibited similar biphasic phenomenon. Antibody production as assessed by enumeration of the sheep red blood cell (SRBC)-specific plaque-forming cells (PFC) indicated a significant suppression of PFC in animals exposed to 166 and 790 mg/L benzene. A decrease in the α-SRBC-antibody titer corresponded to the numbers of PFC. The findings suggest that oral ingestion of benzene, at the concentrations utilized, produced a biologically significant immunotoxic effect on both the humoral and cellular immune responses.