IMMUNOTOXICITY OF AMINOCARB .2. EVALUATION OF THE EFFECT OF SUBLETHAL EXPOSURE TO AMINOCARB ON BONE-MARROW CELLS BY FLOW-CYTOMETRY

The potential immunotoxic effect of the carbamate pesticide aminocarb on murine bone marrow cell subpopulations was evaluated by flow cytometry, C57B1 6 mice were exposed by gavage to sublethal doses of the pesticide and lymphocyte precursors from bone marrow population were stained with PNA lectin and a panel of monoclonal antibodies against cell surface antigens. In regard to the microenvironment-dependent maturation of B lymphocytes, the pesticide effect on the lymphoproliferative potential of bone marrow was assessed by marrow transplantation from aminocarb-exposed donor mice to normal, syngeneic, X-irradiated recipient mice. The sublethal exposure of 0.08-5.0 mg/kg body wt aminocarb to donor animals did not affect regenerating bone marrow in the recipient mice. No marked effect on bone marrow cell number was noted in pesticide-exposed animals. However, a marked shift in surface IgM density on marrow B cells was noted at 0.08 and 0.31 mg/kg body wt aminocarb. This was correlated with decreased cell frequency in G0 G1 phase and increased frequency of cells in the S phase of the cell cycle. Thus, altered maturation of B lymphocytes, expressed as a shift in the density of surface IgM on mature B cells and not the lymphocyte count, was related to the direct effect of aminocarb and/or to the pesticide-related changes in bone marrow microenvironment. Overall, exposure to the carbamate pesticide aminocarb activated the cell maturation process in bone marrow. © 1990.