ABSTRACT
Introduction: In Argentina, multiple sclerosis patients (MSp) are vaccinated against SARS-CoV-2 using different formulations upon availability, including viral vector/inactivated virus/mRNA vaccines, at distinct times between doses. The real-world effectiveness of these unique vaccination schedules is scarce, so asthe efficacy to mount an appropriate immune response even more in MSp under treatment (DMTs) Aims: To analyze the presence of reactive CD4+ and CD8+ T cells for SARS-CoV-2, IgG and IgM anti-Spike and anti-RBD, in MSp after receiving a 3rd vaccine dose Methods: 27 MSp and 9 healthy controls (HC) were included in this study. SARS-CoV-2-reactive T cells were analysed with a T Cell Analysis Kit from Miltenyi as described by the manufacturer. In brief, peripheral blood mononuclear cells (PBMCs) were cultured with a pool of lyophilized peptides, consisting of 15-mer sequences with 11 amino acids overlap, covering the complete protein coding sequence (aa 5-1273) of the surface or Spike glycoprotein (S) of SAR-CoV-2 and controls. After stimulation, the cells were stained with the live/dead marker, washed, fixed, permeabilized and stained for lineage and activation markers as well as cytokines. Cells were analysed using a flow cytometer. Doublets, debris, and dead cells as well as CD14+ and CD20+ cells were excluded. Cells were pregated on CD3 as well as CD4 and CD8. For reactive CD4 T cells CD154 and TNF-alpha were assessed on CD4+ T cells while TNF-alpha and IFN-gamma in CD8+ T cells Results: IgG antibodies (Ab) against S and RBD were found in all analysed HC, while in 22 and 20 out of a total of 27 MSp. Levels of IgG against S were lower in MSp vs HC. IgM levels against RBD were found in all HC and MSp, but 8 MSp had low levels of those Ab.There were no differences between HC and MSp in the % of reactive CD4+ T cells to S (p= 0.151). However, we found a lower % of reactive CD8+ T cells in MSp than HC (p= 0.026). Actually, CD8+ T cells were not detected in 4 out of 5 MSp treated with Fingolimod (FTY) but were present in all patients treated with monoclonal Ab, IFN or DMF. Furthermore, MSp treated with FTY had lower values of reactive CD4+ T cells and IgG anti-RBD than patients receiving other DMTs Conclusion(s): Most MSp vaccinated against SARS-CoV-2 present some humoral and cellular response to SARS-CoV-2. This humoral and cellular response would be lower in MSp treated with FTY.