Alterations of T cell distribution and functions in prenatally cypermethrin-exposed rats: possible involvement of catecholamines.

The synthetic pyrethroid insecticide, cypermethrin (50 mg/Kg) was given during gestation to pregnant rats by gavage in corn oil. Prenatal cypermethrin-exposure induces a marked and long-lasting increase of adrenaline (A) and noradrenaline (NA) plasma concentrations. The enhancement of plasma catecholamine levels was accompanied by a marked increase of CD5+, CD4+, and CD8+ total T cell numbers in the peripheral blood, while in the spleen a reduction of all T cell subsets was observed. In addition, peripheral blood lymphocytes (PBL) from rats prenatally exposed to cypermethrin showed an enhanced capability to proliferate in response to different doses of Concanavalin A (ConA), or human recombinant interleukin-2 (hrIL-2), whereas an impaired proliferative response was observed in the spleen. The percent increase of NA, but not A plasma concentrations paralleles the immunomodulatory effects induced by cypermethrin neonatal exposure on T cell distribution and mitogen-induced proliferation in the peripheral blood and spleen. Collectively, our results suggest that the changes in mitogen-induced proliferative responses in the peripheral blood and spleen of prenatally cypermethrin-exposed rats may be attributable to pesticide-induced catecholamine release, which causes an increased output of CD5+, CD4+, and CD8+ T cells from the spleen to the peripheral blood, and a consequent lymphocytosis.