Recall vaccination increases detectable B-cell reactivity in persons with multiple sclerosis treated with ocrelizumab

BACKGROUND: Utility of repeated boosts of anti-SARS-CoV-2 vaccination in persons with MS (pwMS) treated with ocrelizumab is questioned. OBJECTIVE: Investigate antiviral antibody and T-cell responses after mRNA vaccination for SARS-CoV-2 in ocrelizumab-treated pwMS. METHODS: Peripheral blood mononuclear cells were stimulated with SARS-CoV-2 peptide pools and T-cell reactivity was assessed by ELISPOT for IFN-γ detection, and by multiparametric flow cytometry analyses for assessment and characterization of T-cell activation. Anti-SARS-CoV-2 spike and nucleocapsid antibodies were analyzed in plasma of pwMS using two commercial platforms. RESULTS: ELISPOT assay against the spike protein of SARS-CoV-2 showed that COVID vaccination with mRNA results in the development of a robust specific T-cell reactivity that is sustained over repeated cycles of vaccination and tends to decline 2 years after last boost. Flow cytometry analysis following stimulation with SARS-CoV-2 peptide pools confirmed the presence of CD8+ T memory stem cells. CD8+ T memory stem cells, in particular, increased after repeated boosts of vaccination, as occurred for anti-SARS-CoV-2 antibodies. CONCLUSIONS: Repeated cycles of vaccination increase T and B-cell reactivity against SARS-CoV-2.