Memory B Cells Provide Long-Term Protection to Vaccinated Kidney Transplant Recipients Against SARS-CoV-2 Variants

Area of Science:

• Immunology
• Transplantation
• Infectious Diseases

Background:

• Kidney transplant recipients (KTRs) face high COVID-19 risks.
• Vaccination provides short-term antibody protection, but its duration is unclear.
• Germinal center reactions are essential for antibody generation in KTRs.

Purpose of the Study:

• To analyze the longitudinal immune response to COVID-19 vaccination in KTRs.
• To investigate the long-term protective mechanisms against SARS-CoV-2 variants in KTRs.
• To understand the role of humoral memory in vaccine efficacy for KTRs.

Main Methods:

• Longitudinal analysis of immune response in 33 KTRs post-vaccination.
• Retrospective study of severe COVID-19 risk in 274 KTRs.
• Assessment of antibody titers, neutralizing capacity, and memory B cell responses.

Main Results:

• Antibody titers declined rapidly in KTRs, with 2/3 losing neutralizing capacity against variants within months.
• Despite waning antibodies, severe COVID-19 risk remained low in KTRs.
• Memory B cells targeting conserved epitopes persisted and rapidly produced antibodies upon re-exposure.

Conclusions:

• Humoral immunity in KTRs has two layers: rapidly fading serology and durable cellular memory.
• Memory B cells provide sustained protection against COVID-19 variants in KTRs.
• Cellular memory is key for long-term vaccine efficacy in immunocompromised individuals like KTRs.