Post-test analysis, OCR vs FTY p=ns and FTY vs NAT p=0,0058 and OCR vs NAT p=ns). group of age and sex Sancycline matched healthy donors (HD) were included as reference group. Statistical analysis was performed using GraphPad Prism 8.2.1. Results Thirty PwMS and 9 HDs were enrolled. All the patients were unfavorable for anti-N antibody detection, nor reported previous symptoms of COVID-19. Peripheral blood lymphocyte counts were assessed in PwMS showing: (i) reduction of circulating B-lymphocytes in PwMS on ocrelizumab; (ii) reduction of peripheral blood B- and T-lymphocyte complete counts in PwMS on fingolimod and (iii) normal B- and T-lymphocyte complete counts with an increase in circulating CD16+CD56+ NK-cells in PwMS on natalizumab. Three patterns of immunological responses were recognized in PwMS. In patients on ocrelizumab, anti-S antibody were lacking or reduced, Sancycline while T-cell responses were normal. In patients on fingolimod both anti-S titers and T-cell mediated responses were impaired. In patients on Sancycline natalizumab both anti-S titers and T-cell responses were present and comparable to those observed in HD. Conclusions The evaluation of T-cell responses, anti-S titers and peripheral blood lymphocyte absolute count in PwMS on DMTs can help to better characterize the immunological response after SARS-CoV-2 vaccination. The evaluation of T-cell responses in longitudinal cohorts of PwMS will help to clarify their protective role in preventing SARS-CoV-2 contamination and severe COVID-19. The correlation between DMT treatment and immunological responses to SARS-CoV-2 vaccines could help to better evaluate vaccination strategies in PwMS. strong class=”kwd-title” Keywords: T-lymphocyte, peptides, IGRA, ocrelizumab, fingolimod, natalizumab, CD20, COVID Introduction Since December 2019 the Severe Acute Respiratory Syndrome CoronaVirus-2 (SARS-CoV-2) has spread worldwide, causing the coronavirus disease-2019 (COVID-19) (1). In 2020, new SARS-CoV-2 vaccines with different designs have been developed and authorized for human use (2). Specifically, the mRNA vaccine mRNABNT162b2 (Comirnaty?) has been widely employed in the Italian populace, including fragile and immunocompromised subjects (3). Data on specific anti-Spike (S) antibody production and their protective role in vaccinated subjects are accumulating, while little is known around the T-cell response after vaccination, especially in immunosuppressed subjects (4). Several studies have exhibited an impairment of anti-SARS-CoV-2 antibody production in people with multiple sclerosis (PwMS) receiving specific disease modifying therapies (DMTs), such as the sphingosine-1-phosphate receptor modulator fingolimod or the anti-CD20 drug ocrelizumab, after either natural contamination or vaccination (5C7). Moreover, Achiron et?al. and Sormani et?al. showed Rabbit polyclonal to ZNF131 poor seroconversion rates after SARS-CoV-2 vaccination in PwMS receiving ocrelizumab and fingolimod (8, 9), stimulating a argument on timing and recommendations on SARS-CoV-2 vaccination in PwMS on different DMTs (10, 11). T-cell specific immunity represents a fundamental aspect for the evaluation of vaccine response and protection from SARS-CoV-2. Recently, in a rhesus macaques model, McMahan et?al. exhibited that this depletion of CD8+ T-cells in convalescent animals, partially abrogated the protective efficacy of natural immunity in rechallenge with SARS-CoV-2, suggesting a role for cellular immunity in subjects Sancycline with waning or sub-protective antibody titers (12). We have previously investigated SARS-CoV-2 specific T-cell responses in PwMS on ocrelizumab treatment, healed from COVID-19, using an interferon (IFN)- release assay (IGRA) after overnight stimulation of whole blood with SARS-CoV-2 specific peptide libraries. Despite the lack of an antibody response to the natural infection, we were able to identify a specific T-cell response in all the healed subjects included in the study (13). Here we aimed to characterize specific B- and T-cell responses towards Spike protein of SARS-CoV-2 in PwMS receiving three different types of DMTs (ocrelizumab, fingolimod and natalizumab), after two-dose vaccination with the mRNA vaccine Comirnaty?, evaluating also the peculiar changes induced by the DMTs on peripheral blood lymphocyte counts. Methods Study Populace and Blood Sampling The study was approved by the local Ethic Committees (Protocol VaRIA-BT-SARS.