Limited immunotoxic potential of technical formulation of the herbicide atrazine (AAtrex) in mice

Immunotoxicity of the technical atrazine formulation, AAtrex, was examined in C57B1/6 female mice following a sublethal exposure to equivalent 1/2–1.64 LD₅₀ doses of the herbicide. Animal weight was not affected by the herbicide exposure. No dose-related changes could be concluded for fluctuations in organ weight, changes in the spleen cell number and cell viability. Furthermore, cytofluorometric studies showed no significant changes in the frequency of L3T4-positive and Lyt-2-positive T-cells. Functional in vitro assays of mitogen activation showed no marked effects of AAtrex exposure on lymphocyte stimulation by lipopolysaccharide (LPS), phytohemagglutinin (PHA) and concanavalin A (Con-A). In addition, sublethal exposure to AAtrex did not affect interleukin-2 (IL-2) production by splenic cells. Furthermore, no doserelated effect could be concluded from a transient suppression of a primary humoral IgM response to sheep erythrocytes (SRBC) as well as from a transient inhibition of a specific T-cell response to alloantigens in mixed lymphocyte reaction (MLR). Exposure to equiv. 1/2?1/16 LD₅₀ doses augmented phagocytic activity of peritoneal macrophages, without any visible AAtrex dose-related effect. Normal humoral and cellular responses were restored at 14–40 days after the herbicide exposure. Overall, transient and reversible immunosuppression of humoral-mediated and cell-mediated responses and activated macrophage phagocytic activity could not be attributed to the direct chemical-related effect of sublethal exposure to AAtrex.