Decreased Expression of B cell Maturation Antigen in Patients with Common Variable Immunodeficiency

Abstract

Common variable immunodeficiency (CVID) is a heterogeneous group of diseases characterized by hypogammaglobulinemia, leading to recurrent infections. Defect in maturation of B cells into functional plasma cells is the most principal defect in CVID. B cell maturation antigen (BCMA) is an essential molecule for survival of long-lived plasma cells. The aim of this study is to evaluate BCMA expression on B cells as well as count peripheral blood plasmablast cells in CVID patients compared with healthy individuals. Blood samples were collected from 15 CVID patients and 15 age-and sex-matched normal controls. Genomic RNA was extracted from peripheral blood mononuclear cell samples using an RNX-Plus Kit. cDNA was synthesized from extracted RNA using a RevertAid First Strand cDNA Synthesis Kit. Synthesized cDNA was used as a template for reverse transcription polymerase chain reaction (RT-PCR) to measure BCMA gene expression by Maxima SYBR Green/ROX qPCR Master Mix Kit (Thermo Scientific). Flow cytometry was used to measure plasmablast counts in the peripheral blood. RT-PCR results showed that the expression of BCMA in CVID patients compared with control subjects was significantly decreased and this decrease was statistically significant (P < 0.046). Accordingly, the flow cytometric results demonstrated that the mean percentage of plasmablast cells and BCMA expression in patients was significantly (P < 0.002) decreased in comparison with the control group. Our data show that decreased BCMA expression as well as reduction of plasmablast cell frequency in CVID patients could be involved in development of CVID.