Germinal center responses to SARS-CoV-2 mRNA vaccines in healthy and immunocompromised individuals

Vaccine-mediated immunity often relies on the generation of protective antibodies and memory B cells, which commonly stem from germinal center (GC) reactions. An in-depth comparison of the GC responses elicited by SARS-CoV-2 mRNA vaccines in healthy and immunocompromised individuals has not yet been performed due to the challenge of directly probing human lymph nodes. Herein, through a fine-needle aspiration-based approach, we profiled the immune responses to SARS-CoV-2 mRNA vaccines in lymph nodes of healthy individuals and kidney transplant recipients (KTXs). We found that, unlike healthy subjects, KTXs presented deeply blunted SARS-CoV-2-specific GC B cell responses coupled with severely hindered T follicular helper cell, SARS-CoV-2 receptor binding domain-specific memory B cell, and neutralizing antibody responses. KTXs also displayed reduced SARS-CoV-2-specific CD4 and CD8 T cell frequencies. Broadly, these data indicate impaired GC-derived immunity in immunocompromised individuals and suggest a GC origin for certain humoral and memory B cell responses following mRNA vaccination. [Display omitted] •Human GC responses to SARS-CoV-2 vaccines are restricted to draining lymph nodes•Vaccine-induced GC responses are associated with SARS-CoV-2 neutralizing antibodies•Kidney transplant recipients lack GC responses to SARS-CoV-2 vaccines•Vaccines expand S+RBD− memory B cells in healthy donors and transplant recipients Fine-needle aspiration of lymph nodes in humans reveals that SARS-CoV-2 vaccination induces neutralizing antibody-producing germinal centers, enhanced by repeated vaccination. Conversely, in patients receiving immunosuppressant medication, this process is disrupted, resulting in stunted protective immune responses, highlighting issues about vaccine and booster efficacy in patients with compromised immune systems.