B Cell Depletion and SARS-CoV-2 Vaccine Responses in Neuroimmunologic Patients.

OBJECTIVE: The study was undertaken to assess the impact of B cell depletion on humoral and cellular immune responses to severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) vaccination in patients with various neuroimmunologic disorders on anti-CD20 therapy. This included an analysis of the T cell vaccine response to the SARS-CoV-2 Delta variant. METHODS: We investigated prospectively humoral and cellular responses to SARS-CoV-2 mRNA vaccination in 82 patients with neuroimmunologic disorders on anti-CD20 therapy and 82 age- and sex-matched healthy controls. For quantification of antibodies, the Elecsys anti-SARS-CoV-2 viral spike (S) immunoassay against the receptor-binding domain (RBD) was used. IFN-gamma enzyme-linked immunosorbent spot assays were performed to assess T cell responses against the SARS-CoV-2 Wuhan strain and the Delta variant. RESULTS: SARS-CoV-2-specific antibodies were found less frequently in patients (70% [57/82]) compared with controls (82/82 [100%], p < 0.001). In patients without detectable B cells (<1 B cell/mcl), seroconversion rates and antibody levels were lower compared to nondepleted (≥1 B cell/mcl) patients (p < 0.001). B cell levels ≥1 cell/mcl were sufficient to induce seroconversion in our cohort of anti-CD20 treated patients. In contrast to the antibody response, the T-cell response against the Wuhan strain and the Delta variant was more pronounced in frequency (p < 0.05) and magnitude (p < 0.01) in B-cell depleted compared to nondepleted patients. INTERPRETATION: Antibody responses to SARS-CoV-2 mRNA vaccinnation can be attained in patients on anti-CD20 therapy by the onset of B cell repopulation. In the absence of B cells, a strong T cell response is generated which may help to protect against severe coronavirus disease 2019 (COVID-19) in this high-risk population. ANN NEUROL 2022;91:342-352.

Immunology of COVID-19 and disease-modifying therapies: The good, the bad and the unknown.

OBJECTIVE: The outbreak of the SARS-CoV-2 pandemic, caused by a previously unknown infectious agent, posed unprecedented challenges to healthcare systems and unmasked their vulnerability and limitations worldwide. Patients with long-term immunomodulatory/suppressive therapies, as well as their physicians, were and are concerned about balancing the risk of infection and effects of disease-modifying therapy. Over the last few months, knowledge regarding SARS-CoV-2 has been growing tremendously, and the first experiences of infections in patients with multiple sclerosis (MS) have been reported. METHODS: This review summarizes the currently still limited knowledge about SARS-CoV-2 immunology and the commonly agreed modes of action of approved drugs in immune-mediated diseases of the central nervous system (MS and neuromyelitis optica spectrum disorder). Specifically, we discuss whether immunosuppressive/immunomodulatory drugs may increase the risk of SARS-CoV-2 infection and, conversely, may decrease the severity of a COVID-19 disease course. RESULTS: At present, it can be recommended in general that none of those therapies with a definite indication needs to be stopped per se. A possibly increased risk of infection for most medications is accompanied by the possibility to reduce the severity of COVID-19. CONCLUSIONS: Despite the knowledge gain over the last few months, current evidence remains limited, and, thus, further clinical vigilance and systematic documentation is essential.