Immunophenotyping analysis of PD-L1-deficient leukocytes. Freshly drawn whole-blood leukocytes were analyzed by flow cytometry. (A) Absolute cell numbers were determined with Trucount Absolute Counting Tubes. (B–D) Frequencies of the given leukocyte subsets within each parental subset (indicated at the top of the plots). (E) Gating strategy for circulating T_FH (cT_FH) cells. (F) Representative plots for cT_FH cells. (G) Percentage of cT_FH cells. In A–D and G, bars represent the mean and SEM.