POS0003 RITUXIMAB THERAPY IN SYSTEMIC LUPUS ERYTHEMATOSUS – TRANSIENT EFFECTS ON AGE ASSOCIATED B-CELLS

Background: Immune system’s abnormalities in SLE involve several subsets of the B-cell compartment, including double negative B-cells (DN) and CD11c+CD21- B cells (also referred to as ABC-age associated cells), which are expanded disease. ABC also known interact with T helper cells, follicular peripheral (1). Rituximab, a chimeric anti- CD20 antibody, depleting is commonly used off-label treatment for patients, especially lupus nephritis. Little on impact depletion such B-T-cell interactions. Objectives: investigate effects rituximab (RTX) frequencies well (T FH , CXCR5+ PD-1+) PH PD-1 high ) CD4+ T-cell subsets. Methods: 15 starting RTX followed longitudinally up two years, were analyzed lymphocyte using multicolor flow cytometry. Cryopreserved PBMC thawed stained at same time together one buffy coat. Around 1 x 10 6 each panel labeled further fluorescent antibodies markers. For panel, anti-CD3, CD14, CD16, CD19, IgD, CD27, CD38, CD11c, CD21 some samples anti-CXCR5 antibodies. anti-CD16, CD19 CD3, CD4, CD8, PD-1, CCR7, CXCR5, CD45RA All patients fulfilled ACR 1982 classification criteria SLE. Cellular changes context clinical information. Results: present cohort, mainly female (86.6%) median age 36.7 (29.8-49.4) disease duration 6.1(1.6-11.8) active SLEDAI-2K baseline 12.0 (8.0-16.0). The frequency age-associated (ABCs; CD27-IgD-CD11c+ CD21-) decreased by 13% (p=0.03) first four months after start, while globally DN (IgD-CD27-) transiently increased around 3% (p=0.15) follow-up. This increase could not be attributed DN1 (CXCR5+CD11c-) or DN2 (CXCR5-CD11c+) but CD11c-CXCR5- (DN3) (increase= 6.7%, p=0.03). In parallel, effector (CCR7- CD45RA+) TEMRA (CD45RA+ CCR7-) follow both CD8+ cells. (CXCR5+ did change rituximab, however decrease was observed most although significant, 2-4 month treatment. either reduce stay (reduction= 0.53, p=0.28). After 11-15 cell reduces -0.5% comparison (p=0.039). SLEDAI correlate (r=0.03, p=0.9). Conclusion: importance - interactions pathogenesis recently strengthened identification /T ABCs respectively. Here, treated SLE, we detect reduction DN3 memory increased. Our data suggests that anti-CD20 mediated affects frequencies, monitoring these specific may clinically relevant. References: [1]Bocharnikov AV, Keegan J, Wacleche VS, Cao Y, Fonseka CY, Wang G, et al. PD-1hiCXCR5- promote responses via MAF IL-21. JCI insight. 2019;4(20) Disclosure Interests: Francesca Faustini Speakers bureau: More than years ago relation any aspect research, Natalie Sippl: None declared, Ragnhild Stålesen: Karine Chemin: Iva Gunnarsson: Vivianne Malmström: declared.