SAT0002 DIFFERENTIAL RECONSTITUTION OF B-CELL SUBSETS IN SYSTEMIC SCLEROSIS PATIENTS AFTER AUTOLOGOUS HEMATOPOIETIC STEM CELL TRANSPLANTATION
Authors: Joao Rodrigues Lima Junior, Lucas CM Arruda, Maynara S. Gonçalves, Julia Tc Azevedo, Daniela A. Moraes, Dimas T. Covas, Maria Carolina Oliveira, Kelen Cr Malmegrim
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Autologous hematopoietic stem cell transplantation (AHSCT) is nowadays a clinical reality as an effective and safe approach to treat systemic sclerosis patients' refractory to conventional therapy using immune suppressive drugs, although its immune mechanisms are still not completely understood<sup>1,2,3</sup>. <h3>Objectives</h3> To evaluate the reconstitution of B-cell subsets in SSc patients following AHSCT. <h3>Methods</h3> Peripheral blood samples were harvested from twenty-four SSc patients before transplantation and at 30, 60, 120, 180 and 360 days post-AHSCT. The immunophenotyping, regulatory B-cell IL-10 production and suppressive assays were assessed by flow cytometry. <h3>Results</h3> Compared to baseline, naïve B-cells (CD19+CD27<sup>-</sup>IgD<sup>-</sup>) significantly decreased in frequency and absolute counts at 30 days post-AHSCT, followed by an increase at 360 days. There was a transient decrease of non-class-switched memory-B-cell (CD19<sup>+</sup>CD27<sup>+</sup>IgD<sup>+</sup>) frequency at 30 days, followed by an increase at 360 days. In addition, mature class-switched memory-B-cells (CD19<sup>+</sup>CD27<sup>+</sup>IgD<sup>-</sup>) and plasma cell (CD19<sup>+</sup>CD27<sup>high</sup>IgD<sup>-</sup>) decreased (P&lt;0.05) respectively at 60 and 360 days post-AHSCT, while the frequency of double-negative B-cell (CD19+CD27<sup>-</sup>IgD<sup>-</sup>) increased at 30 days post-AHSCT. The subset CD20<sup>+</sup>CD43<sup>+</sup>CD27<sup>+</sup>CD69<sup>-</sup> (human B1-cell) showed higher percentage at 30 days, followed by a decrease at 360 days. The regulatory B cell CD19<sup>+</sup>CD24<sup>hi</sup>CD38<sup>hi</sup> (transitional B-cell subset) significantly increased at 360 days, while CD19<sup>+</sup>CD24<sup>hi</sup>CD27<sup>+</sup> Breg (B10 subset) decrease transiently from 30 to 180 days post-AHSCT. The frequency of CD19<sup>+</sup>PD1<sup>+</sup> B-cells transiently increased at 30 days. The frequency of IL-10-producing regulatory B-cells CD19+CD24<sup>hi</sup>CD38<sup>hi</sup> and CD19+CD24<sup>hi</sup>CD27<sup>+</sup> increased post-transplantation. After AHSCT the regulatory B-cell CD19+CD24<sup>hi</sup>CD38<sup>hi</sup> recover their ability to suppress cytokine production by Th1 CD4+ T-cell in vitro. <h3>Conclusion</h3> Following transplantation, SSc patients displayed increased naive-B-cells values and decreased memory B-cells, which might contribute to self-tolerance reestablishment, disease remission and clinical improvement on these patients. SSc patients showed increases of Breg numbers after AHSCT as well as an increase of IL-10 production, suggesting improvements in immunoregulatory mechanisms. <h3>References</h3> [1] Burt, et al. Lancet2013:381(9872):1116–24. [2] van Laar, et al. JAMA2014;311(24):2490–8. [3] Sullivan, et al. N Engl J Med2018;378:35–47. <h3>Acknowledgement</h3> Funding was provided by the Sao Paulo Research Foundation (FAPESP) and Coordination for the Improvement of Higher Education Personnel (CAPES). <h3>Disclosure of Interests</h3> None declared