P0400DECREASED REGULATORY B CELLS AND THEIR ASSOCIATION WITH CLINICAL RESPONSE IN PATIENTS WITH NEW ONSET LUPUS NEPHRITIS

Abstract Background and Aims Studies in lupus nephritis (LN) have shown impairment in both T regulatory (Treg) number and function. However, the data on B regulatory (Breg) is limited in LN. Our objective was to study Breg and Treg populations in newly diagnosed treatment naïve LN and study their change after initiation of immunosuppression. Method Study included 25 patients of newly diagnosed LN of Class III (+V), IV (+V), V and 10 healthy controls (HC). Immunophenotyping was performed for peripheral blood mononuclear cell (PBMCs) samples using fluorochrome labelled monoclonal antibodies for Tregs (CD3+CD4+CD25hiCD127loFoxP3+) and Bregs (CD19+CD5+CD1dhi IL-10+). The cells were expressed as percentage of T and B cells. Each lymphocyte population was analysed at baseline, 2 and 6 months after initiation of immunosuppression which was given as per unit protocol. Results Bregs were significantly decreased compared to HC at baseline (p=0.002). With immunosuppression, Bregs showed significant increase at 2 and 6 months (p=0.008) and from baseline to 6 months (p=0.005). Bregs in responders significantly increased from 2 to 6 months (p= 0.017) and from baseline to 6 month (p=0.020), while they did not in non-responders. Tregs did not differ significantly from HC and did not show significant increase at 2 and 6 months, in both responders and non-responders. Conclusion Breg population in newly diagnosed LN was significantly reduced and increased significantly with immunosuppression. Bregs had an association with renal remission. This underscores the potential role of Bregs in the pathophysiology of LN and their association with clinical response. This could aid in the design of new immunotherapies for treatment of lupus nephritis.