Serological effect of mRNA vaccination against COVID-19 in multiple sclerosis patients treated with immunosuppressive DMTs

ABSTRACT

Background: Immunosuppressive therapies may impact immune response to COVID-19 vaccines in persons with multiple sclerosis (pwMS). Accordingly, effects of vaccination in pwMS treated with disease-modifying therapies (DMTs) need further elucidation. Aim(s) To investigate COVID-19 BNT162b2 vaccine effect concerning antibody seroconversion, T cells-associated cytokines production and immunophenotype assessment in pwMS under three different DMTs cladribine, fingolimod, ocrelizumab. Method(s) Enzyme immunoassay test was used for anti-spike IgG detection in 98 DMTs-treated pwMS completing first vaccination cycle. In a subset of patients (n=47), serum T cells-associated cytokines (GrB, IFN-gamma and TNF-alpha) were quantified using an automatic ELISA (ELLA) and blood immunophenotype was assessed by flow cytometry. ANCOVA followed by post hoc tukey's test was used to compare anti-spike IgG response in the different DMTs, Student's paired t-test was used to evaluate differences between pre- and post-vaccination in pairwise samples and Pearson's correlation was applied to evaluate association between spike-specific IgG antibody titer and lymphocytes count. Result(s) More pwMS treated with ocrelizumab (63%) lacked anti-spike IgG compared to patients treated with cladribine (14%) and fingolimod (20%) (p<0.001). When present, the anti-spike IgG titer in the ocrelizumab group was lower than in cladribine- (p<0.001) and in fingolimod-treated pwMS (p=0.003). No significant differences in lymphocytes count and T-cell associated cytokines were observed in cladribine- and in fingolimod-treated pwMS, while in pwMS on ocrelizumab a significant increase in GrB serum levels (p=0.021) and a trend of increased CD4+ T cells count were observed after vaccination. Specifically considering non-seroconverted ocrelizumab-treated pwMS, a significant increase of GrB serum levels (p=0.008) and of CD4+ T lymphocytes count (p=0.040) was foundafter vaccination and a negative correlation was observed between anti-spike IgG production and CD4+T cells count (rho=-0.452, p=0.014). Conclusion(s) Our data confirmed differences in spike-specific antibodies among different DMTs and provided evidence of T-cell immunity preservation and activations after BNT162b2 vaccination in ocrelizumab-treated pwMS, specifically in pwMS patients lacking anti-spike IgG, suggesting a protective T-cell response that might explain why the ongoing treatment with ocrelizumab is not associated with a higher risk of COVID-19 infection.