IMMUNOTOXICITY OF MONO-NITROTOLUENES IN FEMALE B6C3F1 MICE .2. META-NITROTOLUENE

The nitrotoluenes are chemicals used in dyes, agricultural products, p harmaceuticals and explosives. In the present studies, the toxicology and immunotoxicity of meta-nitrotoluene (m-nitrotoluene) were evaluate d. Mice, exposed to m-nitrotoluene at dose levels of 200, 400 and 600 mg/kg/body weight for 2 weeks by gastric gavage, gained body weight ov er the treatment period to a slightly greater extent than the control groups. Of the selected organs weighed, the liver and kidney of mice e xposed to m-nitrotoluene were increased in weight while the thymus wei ght was decreased. The liver of mice exposed to m-nitfotoluene, but no t ortho-nitrotoluene, showed slight to moderate swelling of the hepato cytes adjacent to the central veins. The hepatocyte swelling appeared to be reversible and there was no evidence of necrosis. The hematology and serum chemistries examined were unaffected by m-nitrotoluene expo sure although there were modest decreases in the percentage of polymor phonuclear leukocytes and eosinophils in differential blood counts. Bo ne marrow cellularity and the number of CFU/M and CFU/GM were unaffect ed by m-nitrotoluene exposure. m-Nitrotoluene suppressed the IgM respo nse to sRBC and the DHR response to KLH. There was a slight (8%) decre ase in the percentage of B lymphocytes in the spleen. The response to the T cell mitogens was suppressed by as much as 39%. Fc-mediated adhe rence and phagocytosis of chicken erythrocytes and Mt cell activity we re increased dose dependently in mice exposed to m-nitrotoluene. Sever al immune parameters were unaffected by exposure to m-nitrotoluene, in cluding the IgG response to sRBC, responses to the B cell mitogen LPS and to allogeneic cells, and serum interferon levels. Resistance to St reptococcus pneumoniae and Plasmodium yoelii were unaffected also. Res istance to the tumor model PYB6 was increased. Exposure of mice to m-n itrotoluene decreased resistance to Listeria monocytogenes. The decrea sed resistance to L. monocytogenes may be related to an effect on T ce lls, evidenced by a decrease in T cell numbers and in the DHR.