ABSTRACT
Background: Immunodeficient (ID) patients are among risk groups for severe disease after SARS-CoV2 (CoV2) infection. Despite high population immunity, ID patients remain difficult to medically advice due to their impaired immunity during an evolving CoV2 strains pandemic. Aim: We examined if durable immunisation to CoV2 infection or vaccination is developed. Serology cannot answer this since IgG replacement therapy now contains CoV2 antibodies. Instead, a cellular diagnostic test for patients' CoV2 memory T cells was used Methods: We included 13 ID patients (aged 34-78;7 female) who were vaccinated against CoV2 or previously infected: 5 with common variable immunodeficiency (CVID) and 8 with B cell deficiency (BCD) due to anti-CD20 or BTK inhibition therapy. Peripheral blood mononuclear cells isolated from whole blood were cultured with CoV2 spike protein or peptides for 7 days, then measured for T cell activation markers by flow cytometry. Results: CoV2 spike specific CD4 or CD8 T cells were detectable in 7/8 BCD and all CVID patients. However, only 3/5 CVID and 6/8 BCD patients had both CD4 and CD8 T cell responses. Conclusion: Genuine CoV2 T cell responses are detectable with a cellular diagnostic test in CVID and BCD patients after immunisation. As ID patients are heterogenous, a diagnostic test for memory T cells against CoV2 gives clinicians evidence of a patient's own immune response beyond passive IgG replacement therapy. This aids in consulting advice for infection avoidance strategies and indication for urgent treatment with monoclonal antibodies against CoV2.
ABSTRACT
The 2019 novel SARS-CoV-2 pandemic has claimed many lives and disrupted people's quality of life. Diagnostic tests not only confirm past exposure but offer key information to guide patients' healthcare options Current diagnostics for SARS-CoV-2 virus presence or antibodies lack evidence of longer-lasting cellular immunity, partly due to more complex cell culture-based techniques compared to serological tests. We aimed to (1) develop an in vitro flow cytometric diagnostic immunoassay and (2) determine if lasting memory helper CD4 and cytotoxic CD8 T cell activations are distinct between unexposed and convalescent individuals Peripheral blood mononuclear cells (PBMCs) isolated from whole blood of unexposed (n = 10) or convalescent (n = 30) individuals were cultured for 5 days with individual SARS-CoV-2 recombinant proteins or self-designed peptides including the spike, membrane and nucleocapsid proteins. Specific activation of memory T cells and B cells against SARSCoV- 2 antigens were determined by the upregulation of activation markers (CD4 T cells: CD134+ CD137+;CD8 T cells: CD69+ CD137+;CD19 B cells: CD38+). We show both activated T cells and B cells are detectable against all tested antigens, and distinguishable between unexposed and convalescent individuals up to 11 months post-infection. Therefore, with this diagnostic tool, we propose that it would benefit immunocompromised individuals who are unable to mount sustained antibody responses and to study immune correlates of protection, thus enhancing knowledge of the Covid19 disease in a wider range of patient groups.