Humoral- and T-Cell-Specific Immune Responses to SARS-CoV-2 mRNA Vaccination in Patients With MS Using Different Disease-Modifying Therapies

Abstract

Background and objectives: To evaluate the immune-specific response after full severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination of patients with multiple sclerosis (MS) treated with different disease-modifying drugs by the detection of both serologic and T-cell responses.

Methods: Healthcare workers (HCWs) and patients with MS, having completed the 2-dose schedule of an mRNA-based vaccine against SARS-CoV-2 in the past 2-4 weeks, were enrolled from 2 parallel prospective studies conducted in Rome, Italy, at the National Institute for Infectious diseases Spallanzani-IRCSS and San Camillo Forlanini Hospital. Serologic response was evaluated by quantifying the region-binding domain (RBD) and neutralizing antibodies. Cell-mediated response was analyzed by a whole-blood test quantifying interferon (IFN)-γ response to spike peptides. Cells responding to spike stimulation were identified by fluorescence-activated cell sorting analysis.

Results: We prospectively enrolled 186 vaccinated individuals: 78 HCWs and 108 patients with MS. Twenty-eight patients with MS were treated with IFN-β, 35 with fingolimod, 20 with cladribine, and 25 with ocrelizumab. A lower anti-RBD antibody response rate was found in patients treated with ocrelizumab (40%, p < 0.0001) and fingolimod (85.7%, p = 0.0023) compared to HCWs and patients treated with cladribine or IFN-β. Anti-RBD antibody median titer was lower in patients treated with ocrelizumab (p < 0.0001), fingolimod (p < 0.0001), and cladribine (p = 0.010) compared to HCWs and IFN-β-treated patients. Serum neutralizing activity was present in all the HCWs tested and in only a minority of the fingolimod-treated patients (16.6%). T-cell-specific response was detected in the majority of patients with MS (62%), albeit with significantly lower IFN-γ levels compared to HCWs. The lowest frequency of T-cell response was found in fingolimod-treated patients (14.3%). T-cell-specific response correlated with lymphocyte count and anti-RBD antibody titer (ρ = 0.554, p < 0.0001 and ρ = 0.255, p = 0.0078 respectively). IFN-γ T-cell response was mediated by both CD4⁺ and CD8⁺ T cells.

Discussion: mRNA vaccines induce both humoral and cell-mediated specific immune responses against spike peptides in all HCWs and in the majority of patients with MS. These results carry relevant implications for managing vaccinations, suggesting promoting vaccination in all treated patients with MS.

Classification of evidence: This study provides Class III data that SARS-CoV-2 mRNA vaccination induces both humoral and cell-mediated specific immune responses against viral spike proteins in a majority of patients with MS.

Figure 1. Antibody and T-Cell Responses After SARS-CoV-2 Vaccination in Patients With Multiple Sclerosis

(A) Evaluation of antibody (Ab) response in 78 health care workers (HCWs) and 108 patients with multiple sclerosis stratified according to drug treatment in 4 groups: ocrelizumab (n = 25), fingolimod (n = 35), cladribine (n = 20), and interferon (IFN)–β (n = 28). Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)–specific anti–receptor-binding domain (RBD) Abs were quantified in plasma or sera samples. Anti-RBD immunoglobulin G (IgG) was expressed as binding arbitrary units (BAU)/mL and values ≥7.1 were considered positive. (B) Evaluation of IFN-γ response to spike antigen. IFN-γ was measured by automatic ELISA in plasma harvested from stimulated whole blood samples and shown as median after subtracting the background. Dashed lines identify the cutoff of each test (spike 16 pg/mL and anti-RBD 7.1 BAU/mL). Each black dot represents 1 sample. The red horizontal lines represent the median; statistical analysis was performed using the Mann-Whitney test and p value was considered significant if ≤ 0.0125.

Figure 2. Evaluation of Interferon-γ–Spike-Specific T-Cell Response by Flow Cytometry

Health care workers (HCWs) (n = 7) and patients with multiple sclerosis (MS) (interferon [IFN]–β–treated n = 4; cladribine-treated n = 4) were stimulated for 24 hours with spike peptide pool and the frequency of IFN-γ–specific T cells was evaluated by flow cytometry. Plots show the frequency of IFN-γ–specific T cells in a representative HCW, patient with MS treated with IFN-β, and patient with MS under cladribine within the CD4⁺ subset (A) and CD8⁺ T-subset (B). (C) Frequency of the CD4⁺ and CD8⁺ T-cell responses (after subtraction of the unstimulated condition value) is shown in HCWs and patients with MS. Each dot represents a different HCW or patient with MS and black lines represent medians. Statistical analysis was performed using the Mann-Whitney test and p value was considered significant if ≤0.05.

Figure 3. Correlations Across Humoral and Cell-Mediated Immunity and Lymphocyte Count

(A) Evaluation of correlation between interferon (IFN)–γ levels in response to spike and anti–receptor-binding domain (RBD) antibodies (Abs) in 108 patients with multiple sclerosis (MS). Anti-RBD immunoglobulin G was expressed as binding arbitrary units (BAU)/mL and values ≥7.1 were considered positive. A slight significant correlation was found in patients with MS (ρ = 0.255, p = 0.0078). (B) Evaluation of correlation between IFN-γ levels in response to spike and lymphocyte number in a subgroup of patients with MS (n = 87). IFN-γ levels correlate with lymphocyte number in patients with MS (ρ = 0.569, p < 0.0001). Dashed lines identify the cutoff of each test (spike 16 pg/mL and anti-RBD 7.1 BAU/mL). Each black dot represents 1 sample. Correlations between assays were assessed by nonparametric Spearman's rank tests. A 2-sided p value <0.05 was considered statistically significant.

Figure 4. Correlations Within Humoral Levels (Anti–Receptor-Binding Domain Immunoglobulin G and MNA₉₀)

The correlation between anti–receptor-binding domain (RBD) immunoglobulin G (IgG) levels and neutralizing antibodies (Abs) was evaluated in a subgroup of the (A) enrolled health care workers (HCWs) (n = 69) and (B) patients with multiple sclerosis (MS) under fingolimod therapy (n = 24). Anti-RBD IgG was expressed as binding arbitrary units (BAU)/mL and values ≥7.1 were considered positive; neutralizing antibodies were expressed as the reciprocal of dilution and values ≥10 were considered positive. A strong significant correlation was found in HCWs (ρ = 0.754, p < 0.0001), whereas a moderate correlation was found in patients with MS (ρ = 0.591, p = 0.0024). Dashed lines identify the cutoff of each test (anti-RBD 7.1 BAU/mL and MNA₉₀ 8). Each black dot represents 1 sample. Correlations between assays were assessed by nonparametric Spearman's rank tests. A 2-sided p value <0.05 was considered statistically significant.