Critical role of PD-1/PD-L1 pathway in generation and function of follicular regulatory T cells

The balance between follicular helper T cells (T-FH cells) and follicular regulatory T (Treg) cells (T-FR cells) is one of the key factors for the development of humoral immune responses. How the balance is regulated, however, is largely unknown. In a recent issue of Nature Immunology, Sage et al. revealed a critical role of the programmed death-1 (PD-1)/PD-L1 pathway in TFR cell generation and function, 1 which provides a novel insight into the mechanisms how T-FH and T-FR cells regulate antibody production.