Very low numbers of isotype switched memory B cells (SMB) in patients with CVID, is associated with the development of inflammatory complications. (A) Isotype-switched member B cells and bacterial DNA in patients and controls: The percentage of SM B cells of 57 CVID subjects with 2% or fewer was compared to 59 CVID subjects with more than this number, or 21 normal controls, showing highly significant differences between these groups (Mann–Whitney test P = 0.001). (B) Increased bacterial DNA in subjects with inflammatory complications: Examining 59 CVID subjects with inflammatory conditions as compared to the 57 other CVID subjects without these conditions (or controls), showing highly significant differences between these groups (Mann–Whitney test P = 0.0008).