ABSTRACT
Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has tremendous implications for the management of patients with autoimmune conditions such as multiple sclerosis (MS) under immune therapies targeting CD20+ B cells (aCD20). Objectives: Here, we investigated humoral and cellular immune responses, including anti-spike titers, neutralization against SARS-CoV-2 wild-type (WT), delta, and omicron variant and T cell responses of aCD20-treated relapsing-remitting MS patients following SARS-CoV-2 vaccination compared with healthy controls. Methods: Blood samples were collected within 4-8 weeks following the second vaccination against SARS-CoV-2. Sera were analyzed for anti-SARS-CoV-2 spike antibodies and neutralization capacity against pseudovirus for wild-type (WT), delta, and omicron variant. Peripheral blood mononuclear cells (PBMCs) were stimulated with a SARS-CoV-2 peptide pool and analyzed via flow cytometry. Results: The aCD20-treated MS patients had lower anti-SARS-CoV-2-spike titers, which correlated with B cell repopulation. Sera of aCD20-treated patients had reduced capacity to neutralize WT, delta, and omicron pseudoviruses in vitro. On the contrary, PBMCs of aCD20-treated patients elicited higher frequencies of CD3+ T cells and CD4+ T cells and comparable response of cytotoxic T cells, while Th1 response was reduced following restimulation with SARS-CoV-2. Conclusion: In summary, aCD20-treated patients have a reduced humoral immune response, depending on B cell repopulation, in accordance with preserved cellular immune response, suggesting partial cellular protection against SARS-CoV-2.