CD4 and common variable immunodeficiency: Mononuclear cells from 25 patients with CVID and age and gender‐matched controls were stained with various monoclonal antibodies (anti‐CD4 APC, anti‐CXCR5 FITC, anti‐CCR6 PerCP, and anti‐CXCR3 PE) and isotype controls and analyzed for TFH1 (CD4+CXCR5+CXCR3+CCR6−), TFH2 (CD4+CXCR5+CXCR3−CCR6−), and TFH17 (CD4+CXCR5+CXCR3−CCR6+) cells by multicolor flow cytometry.