Serum IFN-γ is increased in CVID subjects with very low isotype switched memory B cells; these subjects also have increased CXCL9, and more inflammatory complications. (A) Serum IFN-γ and isotype SM B cells. Serum IFN-γ was significantly increased in sera of 88 CVID subjects with the fewest numbers of circulating isotype SM B cells, <2% (Mann–Whitney test, P = 0.03). 10 serums from normal controls are included. (B) Increased CXCL9. CVID subjects (n = 94) had increased serum CXCL9 as compared to 12 healthy controls (Mann–Whitney test P < 0.001). (C) Serum IFN-γ and CXCL9. For 89 CVID subjects, CXCL9 and IFN-γ levels were significantly correlated (Spearman test 4 = 0.4556; P < 0.0001). Subjects in Group 1 (no inflammatory complications) are distinguished from those with these complications (Group 2).