Presenter of 1 Presentation
O134 - IMMUNOMODULATORY EFFECTS OF SARS-COV-2 VACCINES ON REGULATORY T CELLS IN HCV-ASSOCIATED MIXED CRYOGLOBULINEMIC PATIENTS AND HEALTHY DONORS (ID 993)
Abstract
Background and Aims
Besides priming antigen-specific immune responses, new-generation mRNA-based and virus vectored vaccines are endowed with immunomodulatory properties. BioNTech recently developed a noninflammatory mRNA vaccine (MOGm1Ψ) specific for myelin oligodendrocyte glycoprotein (MOG), nearly identical to the Pfizer/BioNTech BNT162b2 vaccine against SARS-CoV-2 except for the lipid capsule, which induced in mice expansion of MOG specific regulatory T cells (Tregs) able to suppress effector T cells and to protect from experimental autoimmune encephalomyelitis. It is not known whether BNT162b2 induces expansion of Tregs and we compared changes in circulating CD4+CD25+CD127low Tregs in subjects vaccinated with BNT162b2 or with the adenovirus vectored ChAdOx1 nCoV-19 vaccine.
Methods
We analyzed in HCV-associated mixed cryoglobulinemic patients and in healthy donors immediately before the first and 8-14 days after the second vaccine dose (BNT162b2 or ChAdOx1 nCoV-19 vaccine), circulating B and T cell subpopulations by flow cytometry and anti-SARS-CoV-2 spike IgG antibodies by ELISA.
Results
After two doses of BNT162b2 the frequency and absolute count of Tregs increased significantly (p<0.01) and durably (at least 6 months) in patients with mixed cryoglobulinemia. In healthy subjects, vaccination with BNT162b2 increased, whereas that with ChAdOx1 nCoV-19 decreased (p<0.01), the number of circulating Tregs.
Conclusions
BNT162b2, likewise tolerogenic MOGm1Ψ in mice, induces expansion of Tregs, whereas ChAdOx1 nCoV-19 induces their reduction. These opposite effects might explain the reportedly higher efficacy of ChAdOx1 nCoV-19 in priming effector T cell responses.