The effects of maneb alone or in combination with lipopolysaccharide on selected immune parameters in prototypical T(H)1 and T(H)2 strains of mice

The fungicide maneb is a widely used pesticide, but there is a lack of knowledge about its immunotoxic effects. Our objective was to determine the effects of exposure to maneb on select immune parameters in C57BL/6 and BALB/c mouse strains and whether its effects are modulated by exposure to lipopolysaccharide (LPS). Maneb (up to 100 mg/kg) was administered by oral gavage for 14 days to 2-month old male mice. Subgroups of mice were challenged with LPS on day 12. At several time points after the initial maneb dose, blood, spleens, and thymuses were collected and processed for cell counting and flow cytometry. Effects observed were due to exposure to maneb alone, LPS alone, or their combination. Strain-dependent effects were detected for some immune parameters. Some of the negative effects observed were decreased thymus cellularity and weight, inhibition of dendritic cell maturation in spleen, and increased B cell numbers. Thus, maneb exposure appears to be immunotoxic, and some of its toxicity is compounded by exposure to LPS.