Activation of CXCR3-negative cTfh, a cTfh subset involved in B cell help for IgG antibody production (20), was significantly reduced in CVID patients as compared to healthy controls (Figure 3D), indicating that impaired cTfh activation in CVID affected this cTfh subset known to be crucial for B cell IgG antibody production (20). The gene discussed is CXCR3; the disease is common variable immunodeficiency.