Low class–switched memory B cells predict the need for continued immunoglobulin replacement following B cell reconstitution after rituximab: a case series and review of the literature

Abstract

Background: Rituximab is a chimeric monoclonal antibody that is used in a wide variety of conditions, ranging from non-Hodgkin lymphoma to autoimmune diseases such as rheumatoid arthritis and multiple sclerosis. It causes depletion in B cells via antagonism of the CD20 receptor, which is important in initiating B cell cycles and differentiation. The function of CD20 is not entirely known, but it has been shown to be necessary for T-independent B cell immune responses. In some patients, hypogammaglobulinemia develops after rituximab treatment for unclear reasons. Methods: We present five cases of patients who received rituximab during their treatment for B cell lymphoma. Results: All of these patients presented with recurrent infections and hypogammaglobulinemia several years after completing chemotherapy, necessitating treatment with immunoglobulin replacement. B cell subset analysis revealed numeric B cell reconstitution; however, when these patients underwent B cell immunophenotyping, it revealed that the class-switched memory B cells (CSMB) (CD27+IgM−IgD−) remained significantly depressed. Conclusion: The low class-switched memory B cells (CD27+IgM−IgD−) may serve as a potential biomarker for the need of continued immunoglobulin replacement therapies.