AB1169 IMMUNOMODULATORY EFFECTS OF SARS-CoV-2 VACCINATION: INCREASE OF REGULATORY T CELLS AFTER mRNA VACCINE

Background Besides the ability to induce antigen-specific responses, vaccines can be endowed with immunomodulatory properties including capacity or downregulate regulatory T cells (Treg) that suppress adaptative and autoreactive immune responses (1). Objectives We asked if an anti-SARS-CoV-2 mRNA vaccine could also accumulation of Treg in patients mixed cryoglobulinemia vasculitis (MCV), who have a deficiency (2) healthy individuals. investigated immunologic variables possibly associated low immunogenicity SARS-CoV-2 MCV (3). Methods analyzed peripheral blood lymphocyte subpopulations serological response 24 9 Healthy donors (HD) before after 2 weeks second dose Pfizer/BioNTech vaccine. Results Among we found 15 responders non-responders. All 5 seronegative treated recently rituximab had <5 B cells/µL, whereas absolute cell count was increased 4 untreated due monoclonal lymphocytosis, representing more than 90% cells, non-Hodgkin lymphoma. The percentage pathologic CD21 significantly patients. Before receiving vaccine, reduced frequency among CD4 + compared HD. After there significant increase percent CD4+ Concerning pre-vaccination distribution subpopulations, percentages counts total CD3 , CD8 HLA-DR activated, CD56 natural killer not reveal any pattern lack Conclusion Our findings show immunoreactivity may expansion anti-SARS-CoV2 cells. References [1]Krienke C. et al. A noninflammatory for treatment experimental autoimmune encephalomyelitis. Science. 2021 Jan 8;371(6525):145-153. [2]Boyer O. CD4+CD25+ T-cell hepatitis C-mixed vasculitis. Blood. 2004 May 1;103(9):3428-30. [3]Visentini M. Flares cryoglobulinaemia vaccination against SARS-CoV-2. Ann Rheum Dis. Nov 24:annrheumdis-2021-221248. Disclosure Interests None declared