Multiple Roles of Antigen-Specific High-Avidity CD4+ T Cells in Humans

Prof. Ueno discusses the high-avidity CD4 T cells, showing that their frequency, subset composition, and strength of activation (measured via IRF4) determine effective immune responses. In COVID-19, high-avidity T cells—mainly TH1 and TFH—correlated with better outcomes, while severe male patients had more inflammatory, low-avidity cells. Vaccine studies revealed that high-avidity TFH cells predict stronger and longer-lasting antibody responses. Overall, measuring T cell avidity provides key insights into infection severity and vaccine effectiveness.