Malathion, lindane, and piperonyl butoxide, individually or in combined mixtures, induce immunotoxicity via apoptosis in murine splenocytes in vitro.

Lindane, malathion, and piperonyl butoxide were cultured singly or as mixtures with murine splenocytes to evaluate changes in cell death and caused cytotoxicity in a concentration- and time-dependent manner. Pesticide mixture studies were then performed based on minimum cytotoxicity concentrations (<LC(25)). Cytologic analysis and the alamarBlue assay revealed that individual pesticides and mixtures of malathion/lindane and malathion/piperonyl butoxide prompted cytotoxicity, which was supported by DNA ladder analysis. Using 7-aminoactinomycin D, apoptosis was quantified at 6.5%, 12.0%, 13.2%, 19.3%, and 23.4% for malathion, lindane, piperonyl butoxide, malathion-lindane, and malathion-piperonyl butoxide, respectively. Staining with 7-aminoactinomycin D and B- or T-cell-specific fluorescent-labeled monoclonal antibodies showed B cells to be more susceptible to malathion and piperonyl butoxide treatments than T cells. Treatment of murine splenocytes in vitro with minimum cytotoxic concentrations of lindane, malathion, and piperonyl butoxide and their mixtures induced apoptosis, the effect elicited by the mixtures being additive compared with the individual pesticide effect.