Seasonal changes and sex differences in peripheral blood γδ T and iNKT cells in healthy Polish adults

Vitamin D regulates not only bone metabolism but also many other processes, including the functioning of lymphocytes. Human T cells have a nuclear receptor for vitamin D (VDR). Studies to date have shown significant seasonal variations in conventional T cell populations in humans living in temperate climates. Objectives. The aim of the current paper was an assessment of seasonal changes of γδ T and iNKT cells in healthy individuals. Material and methods. Peripheral blood was drawn from healthy volunteers – approx. 20 a month – and an additional cohort of 20 volunteers donated blood four times, once every four months. Percentages of γδ T and iNKT cells was assessed with flow cytometry. Results. A pronounced accumulation of iNKT cells was noted in spring, the differences in γδ T cells were less notable. Vitamin D significantly hampers γδ T proliferation in vitro . Conclusions. In the presented article, we show seasonal variability within two populations of unconventional T lymphocytes – γδ T and iNKT.