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Objective B cells alterations play a central role in Systemic lupus erythematosus (SLE) pathogenesis. Indeed, expansion of atypical CD21 low, Tbet+ or CD11c+ B cells has been observed in immune-related disorders, including SLE. BAFF inhibition impacts on peripheral B cells distribution and seems to promote negative selection of activated autoreactive B cells. Thus, we investigated the effect of BAFF inhibition through subcutaneous Belimumab (BLM) on peripheral B cell subpopulations, in particular T-bet+ B cells. Methods We analysed SLE patients (ACR/EULAR 2019 criteria) candidate to BLM due to active disease. As control, we included age-matched healthy donors. Disease activity was assessed by SLEDAI-2 and SLE-DAS in all the established time-points baseline (T0), after 1 (T1), 3 (T3), 6 (T6) and 12 (T12) months. The achievement of remission was registered according to SLE-DAS values and DORIS definition. Flow cytometry was applied to analyse IgD+CD27+ Naïve, IgD+CD27+ Marginal Zone (MZ)-like, IgD-CD27+ switched memory (SW), and IgD-CD27- double negative (DN), atypical CD21 low CD11c + and T-bet + B cell subpopulations. Results We enrolled 16 patients (M/F 3/13; median age 40.5 years, IQR 22.2; median disease duration 102 months, IQR 85.5; median SLEDAI-2k 6, IQR 6; median SLE-DAS 9.73, IQR 7.23) and 13 HD (M/F 2/11, median age 32 years, IQR 28.5). At baseline, SLE showed a significantly higher%T-bet+ in comparison with HD (pConclusions We confirm that atypical T-bet+ B cells are expanded in SLE. Furthermore, BLM treatment induces an early reduction of this B cell subset, in particular in patients achieving remission.
Ceccarelli et al. (Fri,) studied this question.