Sub-chronic effect of perfluorooctanesulfonate (PFOS) on the balance of type 1 and type 2 cytokine in adult C57BL6 mice

As a ubiquitous and highly persistent environmental contaminant, the clear mechanisms to explain any perfluorooctanesulfonate (PFOS)-induced immunotoxicity are still unknown. This study here sought to examine the ability of PFOS to potentially perturb T-helper (T(H))-1 and T(H)-2 cell cytokine secreting activities, as well as to cause shifts in antibody isotype levels, and possible mechanisms involved in PFOS-induced immunotoxicity. Adult male C57BL/6 mice were exposed to PFOS daily via gavage for 60 days [0, 0.5, 1, 5, 25, or 50 mg/kg total administered dose (TAD)]. One day after the final exposure, the ex vivo production of the T(H)1-type cytokines (IL-2 and IFN-gamma), T(H)2-type (IL-4), and IL-10 cytokines by isolated splenocytes, serum levels of immunoglobulin (Ig) were assessed via ELISA or ELISPOT. The results showed that IL-4 secretion was increased at exposure >= 5 mg PFOS/kg TAD in a dose-dependent manner. PFOS exposure increased IL-10 but decreased IL-2 and IFN-gamma formation markedly at 50 mg PFOS/kg TAD. Serum levels of sheep red blood cells (SRBC)-specific IgM synthesis decreased significantly with PFOS exposure in a dose-related manner; serum SRBC-specific IgG, IgG1, and IgE levels increased with 50 mg PFOS/kg TAD regimens. These results indicated that, after a long-term exposure to PFOS, a host's immune state is likely to be characterized by a shift toward a more T(H)2-like state that, in turn, may lead to enhancement of their humoral response and suppression of their cellular response at levels of upper range for occupationally exposed workers or approximately 150-fold for general human population.