Persistent but atypical germinal center reaction among 3rd SARS-CoV-2 vaccination after rituximab exposure

Front Immunol. 2022 Aug 10:13:943476. doi: 10.3389/fimmu.2022.943476. eCollection 2022.

Abstract

Background: Durable vaccine-mediated immunity relies on the generation of long-lived plasma cells and memory B cells (MBCs), differentiating upon germinal center (GC) reactions. SARS-CoV-2 mRNA vaccination induces a strong GC response in healthy volunteers (HC), but limited data is available about response longevity upon rituximab treatment.

Methods: We evaluated humoral and cellular responses upon 3rd vaccination in seven patients with rheumatoid arthritis (RA) who initially mounted anti-spike SARS-CoV-2 IgG antibodies after primary 2x vaccination and got re-exposed to rituximab (RTX) 1-2 months after the second vaccination. Ten patients with RA on other therapies and ten HC represented the control groups. As control for known long-lived induced immunity, we analyzed humoral and cellular tetanus toxoid (TT) immune responses in steady-state.

Results: After 3rd vaccination, 5/7 seroconverted RTX patients revealed lower anti-SARS-CoV-2 IgG levels but similar neutralizing capacity compared with HC. Antibody levels after 3rd vaccination correlated with values after 2nd vaccination. Despite significant reduction of circulating total and antigen-specific B cells in RTX re-exposed patients, we observed the induction of IgG+ MBCs upon 3rd vaccination. Notably, only RTX treated patients revealed a high amount of IgA+ MBCs before and IgA+ plasmablasts after 3rd vaccination. IgA+ B cells were not part of the steady state TT+ B cell pool. TNF-secretion and generation of effector memory CD4 spike-specific T cells were significantly boosted upon 3rd vaccination.

Summary: On the basis of pre-existing affinity matured MBCs within primary immunisation, RTX re-exposed patients revealed a persistent but atypical GC immune response accompanied by boosted spike-specific memory CD4 T cells upon SARS-CoV-2 recall vaccination.

Keywords: SARS-CoV-2; germinal center (GC); memory B cell (MBC); rituximab (RTX); vaccination.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Viral
  • Arthritis, Rheumatoid*
  • COVID-19 Vaccines
  • COVID-19*
  • Germinal Center
  • Humans
  • Immunoglobulin A
  • Immunoglobulin G
  • Rituximab
  • SARS-CoV-2
  • Vaccination

Substances

  • Antibodies, Viral
  • COVID-19 Vaccines
  • Immunoglobulin A
  • Immunoglobulin G
  • Rituximab