Twenty-eight-day perfluorooctanoate exposure does not affect immune cell populations in naïve mice

Perfluorooctanoate (C₇F₁₅CO₂^-, PFOA) is a perfluorinated compound widely used in the production of industrial products, such as non-stick cookware and firefighting foams. Although its production has been phased out in the United States, PFOA remains prevalent in the environment due to its persistence and resistance to degradation. As a result, trace levels of PFOA is detectable in water, soil, biota, and the general population. Environmental and toxicological concerns have emerged due to potential health risks associated with PFOA exposure, including effects on the immune system. Basic underlying knowledge gaps exist for potential effects of PFOA on baseline immune cell maintenance in the absence of overt liver hypertrophy. In this study, we assessed the immune-related effects of 28-day daily PFOA exposure in adult naïve mice, using doses of 20 ng/kg/day, 200 ng/kg/day, 2 μg/kg/day, and 40 μg/kg/day, resulting in mean serum PFOA concentrations of non-detectable, 6.979 ng/mL, 80.03 ng/mL, and 1773 ng/mL respectively, representative of levels seen in the general human population (∼1.5 ng/mL), community-exposed residents (∼225 ng/mL), and occupational workers (∼2000 ng/mL). Evaluation of immune cell populations in bone marrow, thymus, spleen, liver, and lymph nodes, along with serum antibodies indicate that 28 days of PFOA exposure had no effect on proportion and number of immune cell populations nor serum antibodies, except for a slight decrease in serum IgE at the highest dose. By contrast, mice receiving CTX, a known immune suppressant, exhibited a wide array of biological responses, which were absent from PFOA-treated mice. These findings contribute to understanding the potential immune effects of environmentally relevant PFOA exposure.