IMPORTANCE B-cell-depleting therapies may affect the development of a protective immune response following vaccination. Understanding the ability to develop vaccine-specific immunity to COVID-19 in patients with multiple sclerosis (MS) treated with B-cell-depleting therapy is of importance for clinical decisions. OBJECTIVE To assess SARS-CoV-2 vaccine-specific humoral and cellular responses in patients treated with ocrelizumab compared with healthy controls. DESIGN, SETTING, AND PARTICIPANTS This single-center study performed at Hadassah Medical Center in Jerusalem, Israel, included patients with MS treated with ocrelizumab, healthy controls, and untreated patients with MS. Vaccination occurred between December 2020 and April 2021. Participants donated blood 2 to 4 and 2 to 8 weeks after the second vaccine dose for antibody and T-cell assessments, respectively. EXPOSURES All participants received 2 doses of BNT162b2 vaccine (Pfizer/BioNTech) and completed the study. MAIN OUTCOMES AND MEASURES Proportion of patients treated with ocrelizumab with SARS-CoV-2-specific serology and/or T-cell responses following vaccination. All participants underwent SARS-CoV-2 antibody testing; 29 patients treated with ocrelizumab and 15 healthy controls had evaluation of SARS-CoV-2-specific T-cell responses.RESULTS Of 112 participants, 49 (43.8%) had MS and were treated with ocrelizumab (33 [67.3%] female; mean [SD] age, 47.9 [13.3] years), 23 (20.5%) had MS and were not treated with disease-modifying therapies (18 [78.3%] female; mean [SD] age, 49 [13.4] years), and 40 (35.7%) were healthy controls (25 [62.5%] female; mean [SD] age, 45.3 [16] years). Twenty-six of 29 patients (89.7%) treated with ocrelizumab and 15 of 15 healthy controls (100%) had SARS-CoV-2-specific T cells following vaccination at similar levels (mean [SD], 15.4 [7.6] and 14.3 [6.3] spot-forming cells, respectively). Mean antibody titers and positive serology rate were lower in the group of patients treated with ocrelizumab (mean [SD] antibody titers and positive serology rate, 26.2 [49.2] and 376.5 [907.6] AU/mL; 10 of 40 [25%] and 20 of 49 [40.8%] for S1/S2 and receptor-binding domain, respectively) compared with healthy controls (mean [SD] antibody titers and positive serology rate, 283 [100] and 12 712 [9114] AU/mL; 100% S1/S2 and receptor-binding domain) and untreated patients (mean [SD] antibody titers and positive serology rate, 288.3 [113.

Oligodendrocyte progenitor cells (OPCs) are responsible for remyelination in the central nervous system (CNS) in health and disease. For patients with multiple sclerosis (MS), remyelination is not always successful, and the mechanisms differentiating successful from failed remyelination are not well‐known. Growing evidence suggests an immune role for OPCs, in addition to their regenerative role; however, it is not clear if this helps or hinders the regenerative process. We studied the effect of cerebrospinal fluid (CSF) from relapsing MS (rMS) and progressive MS (pMS) patients on primary OPC differentiation and immune gene expression and function. We observed that CSF from either rMS or pMS patients has a differential effect on the ability of mice OPCs to differentiate into mature oligodendrocytes and to express immune functions. CSF of pMS patients impaired differentiation into mature oligodendrocytes. In addition, it led to decreased major histocompatibility complex class (MHC)‐II expression, tumor necrosis factor (TNF)‐α secretion, nuclear factor kappa‐B (NFκB) activation, and less activation and proliferation of T cells. Our findings suggest that OPCs are not only responsible for remyelination, but they may also play an active role as innate immune cells in the CNS.

The presence of increased BAFF, a soluble factor associated with B-cell activation in the proximity of the disease target organ (CSF) in NMO, and its increase in association with immunomodulating treatments, may help our understanding of the immunopathogenetic mechanisms involved in this disease and contribute to more successful and targeted therapeutic intervention.

Anti-KIR4.1 Abs were found in similar proportions of patients with MS and NMO, at a significantly higher level than observed in HCs; consequently, the presence of Abs does not discriminate between these demyelinating diseases. However, anti-KIR4.1 Ab levels differed in MS patients during relapse and remission; as such, they may represent a marker of disease exacerbation.

The introduction of a third‐dose vaccination along with new variants of concern raises questions regarding serology and T‐cell responses in patients with multiple sclerosis (pwMS) treated with B‐cell depletion who develop attenuated humoral response to vaccines. The aim of this study was to longitudinally evaluate humoral and cellular response to SARS‐CoV‐2 mRNA vaccine in ocrelizumab‐treated pwMS before and following a third vaccine dose. Following the third vaccine dose, patients who are low or nonresponders following initial vaccination did not increase antibody titers. In healthy controls and ocrelizumab‐treated pwMS, cellular response decreased 6 months after initial vaccination and increased significantly after the third dose. ANN NEUROL 2022;91:796–800

Fetal neural stem/precursor cells (NPCs) possess powerful immunomodulatory properties which enable them to protect the brain from immune-mediated injury. A major issue in developing neural stem/precursor cell (NPC) therapy for chronic neuroinflammatory disorders such as multiple sclerosis is whether cells maintain their immune-regulatory properties for prolonged periods of time. Therefore, we studied time-associated changes in NPC immunomodulatory properties. We examined whether intracerebrally-transplanted NPCs are able to inhibit early versus delayed induction of autoimmune brain inflammation and whether allogeneic NPC grafts continuously inhibit host rejection responses. In two experimental designs, intraventricular fetal NPC grafts attenuated clinically and pathologically brain inflammation during early EAE relapse but failed to inhibit the disease relapse if induced at a delayed time point. In correlation, long-term cultured neural precursors lost their capacity to inhibit immune cell proliferation in vitro. Loss of NPC immune functions was associated with transition into a quiescent undifferentiated state. Also, allogeneic fetal NPC grafts elicited a strong immune reaction of T cell and microglial infiltration and were rejected from the host brain. We conclude that long-term functional changes in transplanted neural precursor cells lead to loss of their therapeutic immune-regulatory properties, and render allogeneic grafts vulnerable to immunologic rejection. Thus, the immunomodulatory effects of neural precursor cell transplantation are limited in time.

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Background multiple sclerosis (MS) patients are treated with immunomodulatory treatments that can influence their ability to develop a protective antibody response to the SARS-CoV-2 vaccine. Vaccine efficacy is important for treatment decision and for patients’ reassurance. The main objective is to assess antibody response to SARS-CoV-2 vaccine in MS patients treated with cladribine. Methods Serology response was tested in 97 participants, 67 MS patients and 30 healthy controls (HCs), using two independent methods, 2–3 weeks following the second dose of the BNT162b2 vaccine. Results HCs (n=30) and MS patients treated with cladribine (n=32) had 100% positive serology response against the SARS-CoV-2 spike protein following the second vaccine dose (mean S1/S2-IgG and RBD-IgG:284.5±104.9, 13041±9411 AU/mL and 226.3±121.4, 10554±11405 AU/mL respectively). Comparable findings were observed for untreated MS patients, and interferon beta-1a-treated MS patients (mean S1/S2-IgG: 282.1±100.1, 276.9±94.31 AU/mL respectively). No correlation was found between lymphocyte counts, treatment duration, or time between cladribine dose and vaccination, and serology response or antibody titers. Conclusion and relevance Cladribine treated MS patients are able to produce antibodies to the SARS-CoV-2 mRNA vaccine. In the era of the COVID-19 pandemic, it is reassuring and important for both patients and physicians and will allow to develop consensus guidelines.