PD-1 and ICOS are coexpressed in T follicular helper cells but define three stages of maturation of T follicular regulatory cells - Ribeiro, Filipa; Antunes, Diogo; Pires, Ana R.; Rino, José; Filipe, Beatriz; Jesus, Kátia; Correia, Ricardo; Fonseca, Válter R; Kumar, Saumya; Graca, Luis (2025)