Analysis of class-switched memory B cells in patients with common variable immunodeficiency and its clinical implications
Background: Common variable immunodeficiency (CVID) comprises a heterogeneous group of primary immunodeficiency disorders characterized by hypogammaglobulinemia leading to recurrent infections. Some patients with CAD are more susceptible to earlier onset of respiratory disease and bronchiectasis. It has been suggested that memory B cells, characterized by CD27 expression, can be used as a means to classify subsets of CVID patients. Objective: The aim of this study was to classify a sample of Iranian patients with CVID by quantification of peripheral blood memory B cells and immature B cells and to assess the relationship between this classification and the clinical characteristics of the patients. Methods: The study included 29 patients with CVID and 20 healthy controls. Patients were grouped as follows, according to the quantification of peripheral memory B cells: group I had less than 0.4% switched memory B cells (CD27(+), immunoglobulin [Ig] M(-), IgD(-)) in peripheral blood lymphocytes (PBL), while in group 11 switched memory B cells represented more than 0.4% of PBL. Group I patients were further subdivided into groups la and lb according to the proportion of CD21(-) peripheral B cells. The clinical and laboratory findings for the patients were then compared among the 3 groups. Results: The percentage of switched memory B cells (CD27(+)IgM(-)IgD(-) cells in peripheral B lymphocytes) was markedly reduced in CAD patients compared with controls (P < .001). This percentage was less than 0.4% (group 1) in 20 patients (69%) (P < .05). In the remaining 9 patients (group 11) and all healthy controls, the percentage was greater than 0.4%. Bronchiectasis was more frequent in group I than group 11 (P < .05). Following subdivision of group I patients into groups la and lb based on CD21(-) peripheral B cells, the rate of autoimmunity was found to be much higher in group la than group lb. Conclusions: CAD patients with reduced numbers of switched memory B cells are more prone to recurrent respiratory infections and development of bronchiectasis, and as such, need more special care than other CAD patients. Thus, classification of CVID patients by assessment of switched memory B cells could help physicians to predict clinical prognosis of these patients.