INDUCTION OF SERUM BORNE IMMUNOMODULATORY FACTORS IN B6C3F1 MICE BY CARBON-TETRACHLORIDE - EXPOSURE TO CARBON-TETRACHLORIDE PRODUCES AN INCREASE IN B-CELL NUMBER AND FUNCTION

Carbon tetrachloride exposure in mice induces a serum associated immun osuppressive factor(s) that inhibits T-cell dependent immune responses . The objective of the present studies was to characterize the immunom odulatory activity of serum isolated from carbon tetrachloride-treated mice on T-cell independent humoral immune responses. Direct addition of serum isolated from carbon tetrachloride-treated mice (500 mg/kg/da y for 7 days) to naive spleen cell cultures enhanced the antibody form ing cell response to lipopolysaccharide as compared to serum from naiv e or vehicle-treated mice. Enhanced antibody forming cell responses we re also observed when spleen cells isolated from carbon tetrachloride- treated mice were sensitized with this T-cell independent antigen 24 h , but not 48 h or 72 h, following exposure of mice to one dose of 500 or 1000 mg/kg of carbon tetrachloride. Additionally, spleen weight and spleen : body weight ratio were increased in mice sensitized in vivo with sheep red blood cells 24 h after exposure to a single dose of car bon tetrachloride (500 or 1000 mg/kg) as compared to naive antigen sen sitized mice and mice sensitized 48 and 72 h after exposure to carbon tetrachloride. Fluorescence activated cell sorting analysis indicated that daily exposure to carbon tetrachloride (250 or 500 mg/kg for 7 da ys) increased the percentage of B-cells in the spleen without altering the number of T-H-cell or T-C/S cell populations. Taken together, the se results suggest that exposure to carbon tetrachloride induces a ser um borne factor(s) that produces a modest increase in the functional a ctivity and number of B-cells in the spleen.