SARS-CoV-2 T-Cell Responses in Allogeneic Hematopoietic Stem Cell Recipients following Two Doses of BNT162b2 mRNA Vaccine.

Béatrice Clémenceau,Jocelyn Ollier,Audrey Grain,Marianne Coste-Burel,Alice Garnier,Pierre Peterlin,Amandine Le Bourgeois,Marie C Béné,Maxime Jullien,Henri Vié,Thierry Guillaume,Patrice Chevallier

doi:10.3390/vaccines10030448

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.

Highlights

Since its appearance in the late months of 2019, COVID 19 infection has been responsible for more than 5 million deaths worldwide
Reduced vaccine immunogenicity is increasingly reported in this setting [4–8], except in recipients of allogeneic hematopoietic stem cells transplantation (Allo-HSCT), where specific anti-SARS-CoV-2 antibodies can be detected in around 80% of cases [9–12]
This is rather intriguing since weak antibody responses to other vaccines have been well-documented in Allo-HSCT recipients [13], notably during the influenza pandemic of 2009 [14]

Summary

Introduction

Since its appearance in the late months of 2019, COVID 19 infection has been responsible for more than 5 million deaths worldwide. Thanks to the rapid development of anti-SARS-CoV-2 vaccines, it has been possible to consider controlling this pandemic, especially in terms of avoiding severe forms of infection leading to intensive care [1,2] Immunocompromised patients were initially excluded from trials evaluating the safety and efficacy of vaccination. Reduced vaccine immunogenicity is increasingly reported in this setting [4–8], except in recipients of allogeneic hematopoietic stem cells transplantation (Allo-HSCT), where specific anti-SARS-CoV-2 antibodies can be detected in around 80% of cases [9–12]. This is rather intriguing since weak antibody responses to other vaccines have been well-documented in Allo-HSCT recipients [13], notably during the influenza pandemic of 2009 [14]. 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%)

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Results

Discussion

Conclusion