IgD⁺IgM^- B Cells in Common Variable Immunodeficiency

Common variable immunodeficiency (CVID) is the most frequent form of primary hypogammaglobulinemia in adults. In addition to recurrent infections and respiratory manifestations, CVID patients may present several non-infection complications such as autoimmune diseases. The mechanisms that lead to immune dysregulation in CVID are not completely understood. Given the role of IgD on naïve B cells in the maintenance of tolerance and secreted IgD in the respiratory mucosa, we evaluated the frequency of IgD⁺ naïve and IgD⁺ memory B cells in CVID patients. Here, no differences were observed in the percentages and proliferative responses of anergic IgD⁺IgM^-CD27^- B cells between CVID patients, with or without autoimmune disease, and the control group. Interestingly, in the compartment of memory B cells, the percentage of IgD⁺IgM^- cells was higher only in CVID patients with allergic rhinitis/allergic asthma. Our results may indicate that anergic IgD⁺IgM^-CD27^- B cells may not be compromised in our CVID cohort. However, IgD⁺IgM^- memory B cells may play a role in the immunopathogenesis of allergic rhinitis/allergic asthma in CVID patients. Further studies are needed to better understand the participation of IgD⁺IgM^- memory B cells in the immunopathogenesis of allergic rhinitis/allergic asthma in CVID patients.