SARS-CoV-2 T-Cell Responses in Allogeneic Hematopoietic Stem Cell Recipients following Two Doses of BNT162b2 mRNA Vaccine
Béatrice Clemenceau, Thierry Guillaume, Marianne Coste‐Burel, Pierre Péterlin, Alice Garnier, Amandine Le Bourgeois, Maxime Jullien, Jocelyn Ollier, Audrey Grain, Marie C. Béné, Henri Vié, Patrice Chevallier
Abstract
Background: At variance to humoral responses, cellular immunity after anti-SARS-CoV-2 vaccines has been poorly explored in recipients of allogeneic hematopoietic stem-cell transplantation (Allo-HSCT), especially within the first post-transplant years where immunosuppression is more profound and harmful. Methods: SARS-CoV-2 Spike protein-specific T-cell responses were explored after two doses of BNT162b2 mRNA vaccine in 45 Allo-HSCT recipients with a median time from transplant of less than 2 years by using INF-γ ELISPOT assay and flow-cytometry enumeration of CD4+ and CD8+ T lymphocytes with intracellular cytokine production of IFN-γ and TNF-α. Results: A strong TNF-α+ response from SARS-CoV-2-specific CD4+ T-cells was detected in a majority of humoral responders (89%) as well as in a consistent population of non-humoral responders (40%). Conclusions: T-cells are likely to participate in protection against COVID-19 viral infection, even in the absence of detectable antibody response, especially in the first years post-transplant in Allo-HSCT recipients.