Effects of Perfluorohexane Sulfonate Exposure on Immune Cell Populations in Naive Mice.

Perfluorohexane sulfonate (PFHxS) is a member of the per- and polyfluoroalkyls (PFAS) superfamily of molecules, characterized by their fluorinated carbon chains and use in a wide range of industrial applications. PFHxS and perfluorooctane sulfonate are able to accumulate in the environment and in humans with the approximated serum elimination half-life in the range of several years. More recently, some PFAS compounds have also been suggested as potential immunosuppressants. In this study, we analyze immune cell numbers in mice following 28-d repeated oral exposure to potassium PFHxS at 12, 120, 1,200, and 12,000 ng/kg/d, with resulting serum levels ranging up to ∼1,600 ng/ml, approximating ranges found in the general population and at higher levels in PFAS workers. The immunosuppressant cyclophosphamide was analyzed as a positive control. B cells, T cells, and granulocytes from the bone marrow, liver, spleen, lymph nodes, and thymus were evaluated. We found that at these exposures, there was no effect of PFHxS on major T or B cell populations, macrophages, dendritic cells, basophils, mast cells, eosinophils, neutrophils, or circulating Ab isotypes. By contrast, mice exposed to cyclophosphamide exhibited depletion of several granulocyte and T and B cell populations in the thymus, bone marrow, and spleen, as well as reductions in IgG1, IgG2b, IgG2c, IgG3, IgE, and IgM. These data indicate that exposures of up to 12,000 ng/kg of PFHxS for 28 d do not affect immune cell numbers in naive mice, which provides valuable information for assessing the risks and health influences of exposures to this compound.

Effects of PFOS and cyclophosphamide exposure on immune homeostasis in mice.

Perfluorooctane sulfonic acid (PFOS) is member of a class of molecules with fluorinated carbon chains known as polyfluoroalkyls. PFOS have been used to produce a variety of industry and comsumer uses. However, a significant concern is that it accumulates in the environment, including in animals and humans, and that it is a potential immunosuppressant. Here we analyze immune homeostasis in mice following chronic exposure to PFOS at levels up to those historically found in PFOS manufacturing workers. Mice were exposed to 0.15, 1.5, 15, or 50 µg /kg of PFOS for 28 days, after which, B cells, T cells, and granulocytes from the bone marrow, liver, spleen, lymph nodes, and thymus were evaluated. We find that at these exposures, there was no effect of PFOS on major T- or B-cell populations, macrophages, dendritic cells, basophils, mast cells, eosinophils, neutrophils, serum antibodies or select serum cytokines. By contrast, mice exposed the known immunosuppressant cyclophosphamide, which was given at 40 mg/kg for four days, exhibited depletion of several granulocyte, T- and B-cell populations of the thymus, bone marrow, and spleen, as well as circulating IgM and IgE antibodies. These data indicate that exposures of up to 50 µg /kg of PFOS for 28 days does not affect immune homeostasis in mice.