Determination of in vitro immunotoxic potencies of a series of perfluoralkylsubstances (PFASs) in human Namalwa B lymphocyte and human Jurkat T lymphocyte cells

In vitro approaches to investigate the effect of chemicals on antibody production: the case study of PFASs

The increasing variety and quantity of new chemical substances have raised concerns about their potential immunotoxic effects, making it essential to assess their impact on human health. One key concern is the reduction of antibody production, as seen with per- and poly-fluoroalkyl substances (PFASs), commonly known as "forever chemicals." Both in vivo and epidemiological data show that PFASs have immunosuppressive effects, leading to reduced antibody responses, particularly following vaccination. In animal studies, the T cell-dependent (TD) antibody response is the gold standard for assessing chemical effects on immune function. This study utilized two in vitro approaches to investigate the effects of chemicals on antibody production using human peripheral blood mononuclear cells. Initial tests used unstimulated, negative (vehicle), and positive (rapamycin) controls to confirm the robustness of the models. Subsequently, four long-chain PFASs (PFOA, PFOS, PFNA, and PFHxS) were tested. Keyhole limpet hemocyanin (KLH) was used to mimic the TD response, while a TLR9 agonist and IL-2 activated B cells for T cell-independent (TI) immunoglobulin production. The results demonstrated the ability to reproduce TD and TI responses in vitro with robust, reproducible outcomes across a cohort of 20 human donors. The data, consistent with existing literature, showed a significant reduction in anti-KLH IgM production, especially for PFOA in male donors. Similar trends were observed for all PFASs in suppressing total TI IgG and IgM production. These methods closely replicated in vivo conditions, offering a potential alternative to animal models in immunotoxicity assessments.

Perfluoroalkyl substances and immunotoxicity: An in vitro structure-activity relationship study in THP-1-derived monocytes and macrophages

Recently, PFASs toxicity for the human immune system has become a growing concern. However, there is currently limited information on PFASs immunotoxicity beyond PFHxS, PFOA, PFOS, and PFNA. Therefore, it is urgent to close the present knowledge gap by testing a wider range of compounds. In the present study, twelve compounds were tested for a relationship between the chain-length and headgroup of a PFAS and its cytotoxic for THP-1. As such, THP-1, either as monocytes or differentiated macrophages, were exposed to PFASs in a concentration range of 0-800 μM for either 3 or 24 h. After that, cell viability and reactive oxygen species (ROS) generation were assessed using MTT and DCFH assay, respectively. PFASs' cytotoxicity is dependent on both their chain-length and headgroups. Cell viability decreased with increasing chain-length, and FTOHs displayed markedly higher toxicity than PFCAs and PFSAs. PFASs were ranked based on their calculated Relative Potency Factor. The ranking for the cytotoxicity data on monocytes appears to be 6:2 FTOH ≫ PFNA > PFDA > PFOS > PFOA >4: 2 FTOH > PFHxS = PFHxA > PFBA. For macrophages, this ranking was as follows: 6:2 FTOH >4:2 FTOH > PFOS > PFDA > PFNA > PFOA > PFHxS. The results observed for the ROS generating potential differed as FTOHs generated no ROS. Here, the ranking in monocytes was PFOA > PFNA > PFOS > PFHxS > PFDA > PFHxA = PFBS = PFBA. The ranking for macrophages was PFNA > PFDA ≥ PFOA > PFOS > PFHxA > PFHxS > PFBA = PFBS. In conclusion, the carbon chain-length and functional headgroup of a PFAS are major determinants for their toxicity to THP-1 cells. Furthermore, our study demonstrates the most potent cytotoxic effect for FTOHs in vitro, which has not been observed before to the authors' knowledge.