B-cell maturation defects in common variable immunodeficiency and association with clinical features

Summary Aims Patients with common variable immunodeficiency (CVID) often have defects in post-antigenic B-cell differentiation with fewer memory B cells and impaired isotype switching. We aimed to classify CVID patients according to these defects and determine whether this predicted clinical manifestations. Methods We analysed the memory marker CD27, maturation marker CD21, and IgD on peripheral blood B cells from 31 CVID patients and 23 controls using a whole-blood lysis technique, allocated patients according to two classifications ('Freiburg' and 'Paris') and correlated results with clinical manifestations. Results CVID patients had fewer memory (CD27+) B cells and isotype-switched (IgD – ) memory B cells in absolute number and proportion. Many CVID patients had increased immature (CD21 – ) B cells. Lymphoproliferation and autoimmune cytopenias were found almost exclusively in these patients, including Freiburg group Ia (decreased switched memory and increased immature B cells), but also those with normal switched memory and increased immature B cells. The Paris classification was less useful in predicting clinical manifestations. Conclusion CVID is associated with defects in memory B-cell differentiation. Subclassification helps identify patients with clinical manifestations, particularly lymphoproliferation and autoimmune cytopenias in those with impaired B-cell maturation and isotype switching. Routine B-cell phenotyping may assist clinicians in predicting these clinical features.