EFFECT OF 2,4-DICHLOROPHENOXYACETIC ACID, TRIFLURALIN AND TRIALLATE HERBICIDES ON IMMUNE FUNCTION

The commercial formulations of 3 commonly used herbicides (the amine s alt of 2,4-dichlorophenoxyacetic acid, trifluralin and triallate) were evaluated for effects on immune function in male Fisher 344 rats. The herbicides were prepared in an olive oil vehicle and administered by oral gavage twice weekly for 28 d at the following doses: 10.0 mg 2,4- D/kg; 17.5 mg trifluralin/kg; 5.0 mg triallate/kg/treatment. Normal bo dy weight and organ/body weight ratios indicated the rats tolerated th e herbicide treatments without difficulty. Exposure to 2,4-D did not a lter lymphocyte blastogenesis, IgM antibody production (anti-sheep red blood cell), lymphocyte cell surface marker expression or phagocytic function of peritoneal macrophages. Trifluralin acted as a weak mitoge n, but impaired T-lymphocyte blastogenesis induced by phytohemagglutin in and concanaval in A. Other immunological measurements were unaffect ed by trifluralin exposure. Triallate exposure reduced peritoneal macr ophage phagocytosis by 33%, showed weak mitogenic properties and Impai red T-lymphocyte blastogenesis In the presence of phytohemagglutin. Tr iallate also increased the anti-sheep red blood cell response expresse d/spleen by 43%, a phenomenon suggestive of a compensatory response to minimize the impact on overall immune function. The changes In lympho cyte or macrophage function due to the herbicide treatments were not a ssociated with changes In lymphocyte cell surface antigen expression.