Isotype-switched member B cells are inversely related to bacterial DNA in patients. The numbers of isotype SM B cells for the 114 CVID patient cohort were significantly and inversely related to the amount of bacterial DNA for 90 CVID samples (Spearman r, two tailed test, P = 0.02; r = −0.31). Subjects in Group 1 (no inflammatory complications) are distinguished from those with these complications (Group 2).