T cells (T lymphocytes) are white blood cells that play a crucial role in the adaptive immune system. They are formed in the bone marrow and mature in the thymus, where they learn to distinguish between the body's own and foreign structures. T cells coordinate all types of immune cells to control both cellular and antibody-mediated responses. While it is already known that PFAS, also known as eternity chemicals, alter immunity in humans, the specific effects of PFAS exposure in early childhood on the development of T-cells in newborn infants had not yet been investigated.

For this reason, the team of scientists from Rochester studied mother-child couples in the first trimester between 2015 and 2019 as part of the UPSIDE-ECHO cohort. From then until the child's first birthday, the couples were monitored. Various PFAS concentrations of the mothers were quantified in serum in the second trimester using high-performance liquid chromatography as well as tandem mass spectrometry. The abundances of the infants' T lymphocytes were determined at birth and at the age of 6 respectively 12 months using mass cytometry and high-dimensional clustering methods.

The scientists measured that PFAS exposure in the womb correlated with several CD4+ T cell subpopulations in sucklings. The greatest effects were observed in follicular T helper cells and T helper cells type 2 at the age of 12 months. Follicular T helper cells interact with the related follicular B cells. They trigger the formation of germinal centers in the lymphoid tissue and control, among other things, the selection and survival of B cells. T helper cells 2, on the other hand, activate B cells, but they can also send out cytokines if required, whereby certain B cell types are converted into another B cell type. The higher the proportion of PFAS in the mother's body, the more remarkable was the lower proportion of T follicular helper cells and the higher proportion of T helper cells 2 in the child at 12 months of age.

However, further volunteer studies are needed to investigate PFAS-associated T-cell distribution and its role on immune-related health outcomes in children.

Original paper:
Meléndez DC, Laniewski N, Jusko TA, Qiu X, Lawrence BP, Rivera-Núñez Z, Brunner J, Best M, Macomber A, Leger A, Kannan K, Miller RK, Barrett ES, O'Connor TG, Scheible K. In utero per - and polyfluoroalkyl substances (PFAS) exposure and changes in infant T helper cell development among UPSIDE-ECHO cohort participants. Environ Health Perspect. 2025 Jun 9. doi: 10.1289/EHP16726. Epub ahead of print. PMID: 40489731.

More Information:
https://chemtrust.org/pfas/
https://www.niehs.nih.gov/health/topics/agents/pfc