Humoral and Cellular Immunomodulation Induced by Propoxure in C57-bl/6 Mice

Propoxure (PPX) is a well-known carbamate insecticide, which has been used for several decades in the world and Iran in agriculture and public health programs. However, there is no clear investigation toward its immunotoxicity as yet. In this study, we examined the effects of subchronic i.p. exposure of PPX on humoral (PFC & HA) and cellular (DTH) responses, and also monitored T-Cell subtypes using FACS technique. Briefly, female C57b1/6 inbred mice were administered PPX (0.2, 2 and 10 mg/kg/day i.p. [5 inj/wk] for 28 days) or positive and negative controls. On the day 28, mice were examined for DTH, PFC and HA responses to SRBC. Splenocyte single cell suspension was used for measuring the spleen CD4/CD8 percentage and absolute number. In vitro lymphocyte proliferation response to non-specific antigen (PHA) was also measured using MTT method.

Results showed that PPX at 10 mg/kg/day could suppress DTH response and could increase the spleen CD4-/CD8+ T-cell percentage. On the other hand, PPX at medium dose (2 mg/kg) could increase the antibody formation response against SRBC as determined by PFC and HA. Subchronic PPX at low dose (0.2 mg/kg/day) could not show any significant effects on humoral or cellular responses. It could be concluded that, subchronic PPX at high dose (10 mg/kg), possessed cellular immunosuppressive effect. However, PPX at 2 mg/kg does not change cellular response to antigen but can stimulate humoral responses. It seems that PPX has no adverse effects on mice immune system at low doses as 0.2 mg/kg, which is 10 fold greater than PPX Allowed Daily Intake limit.