Post-vaccination SARS-Cov-2 T-cell receptor repertoires in patients with multiple sclerosis and related disorders.

Background: Attenuation in post-vaccination SARS-CoV-2 humoral responses has been demonstrated in people treated with either anti-CD20 therapies or sphingosine-1-phosphate (S1P) receptor modulators. In the setting of disease modifying therapy (DMT) use, humoral response may not correlate with effective immunity, and analysis of vaccine-mediated SARS-CoV-2-specific memory T-cell responses is crucial. While vaccination in patients treated with anti-CD20 agents leads to deficient antibody production, emerging data from live cell assays suggests intact T-cell responses to vaccination. We evaluated post-vaccination SARS-CoV-2 T-cell receptor (TCR) repertoires in DMT-treated patients using the ImmunoSeq assay, an assay that does not require live cells.

Methods: Adults 18-80 years old without prior COVID-19, with neuroimmune conditions, who had been vaccinated with two doses of Pfizer-BioNTech or Moderna mRNA vaccines at least 3 weeks and up to 6 months prior, were recruited. Whole blood was obtained for immunosequencing, and matched serum was obtained for humoral analysis. Immunosequencing of the CDR3 regions of human TCRβ chains was completed using the immunoSEQR Assay (Adaptive Biotechnologies). TCR sequences were mapped across a set of TCR sequences reactive to SARS-CoV-2. Clonal diversity (breadth) and frequency (depth) of TCRs specific to SARS-CoV-2 spike protein were calculated and relationships with clinical variables were assessed.

Results: Forty patients were recruited into the study, aged 25-77, and 27 female. 37 had MS, 2 had neuromyelitis optica spectrum disorder (NMOSD), and 1 had hypophysitis. Subjects treated with anti-CD20 agents and S1P receptor modulators had severely attenuated humoral responses, but SARS-CoV-2-spike-specific TCR clonal depth and breadth were robust across all treatment classes except S1P modulators. No spike-specific or non-spike-specific SARS-CoV-2-associated TCRs were found in those treated with S1P modulators (p = 0.002 for both breadth and depth). Subjects treated with fumarates exhibited somewhat lower spike TCR breadth than subjects treated with other or no DMTs (median 2.27 × 10^-5 for fumarates and 4.96 × 10^-5 for all others, p = 0.008), but no statistically significant difference was demonstrated with spike TCR depth. No other significant associations with DMT type were found. We found no significant correlations between depth or breadth and age, duration of treatment, type of vaccination, or time interval since vaccination.

Conclusion: This is the first study to characterize post-vaccination SARS-CoV-2 TCR repertoires in DMT-treated individuals. We demonstrated a dichotomous response to SARS-CoV-2 vaccination in anti-CD20-treated patients, with severely attenuated humoral response but intact TCR depth and breadth. It is unclear to what degree each arm of the adaptive immune system impacts post-vaccine immunity, both from the standpoint of incidence of post-vaccine infections and that of infection severity, and further clinical studies are necessary. S1P modulator-treated subjects exhibited both severely attenuated humoral responses and absent spike-specific TCR depth and breadth, information which is crucial for counseling of patients on these agents. Our methodology can be used in larger studies to determine the benefit of repeated vaccination doses, including those that are modified to better target modern or seasonal variants, without the use of live cell assays.