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BackgroundIn recent studies, up to half of immunocompromised (IC) subject populations fail to develop antibodies after COVID-19 vaccination.Purpose and MethodsHere, we explore whether T-cells which respond to the spike (S) antigenic sequence and its less conserved S1, and the conserved S2 component are present in serial samples before and after each dose of mRNA1273 or BNT162b2 vaccines in 20 healthy immunocompetent subjects. Single samples from 7 vaccinated IC subjects were also tested. Simultaneously, we measured IgG antibodies to the receptor binding domain (RBD) of S1, and anti-S IgG, and frequencies of monocytic CD14+HLA-DR-(M-MDSC) and polymorphonuclear CD14-CD15+CD11b+ (PMN-MDSC) myeloid-derived suppressor cells.ResultsIn healthy subjects, S1-, S2-, and S-reactive CD4 and CD8 T-cell frequencies showed a numeric but not statistically significant decrease after the first vaccine dose and were accompanied by increased MDSC frequencies (pConclusionsIn healthy immunocompetent subjects, mRNA vaccines induce antibodies to the spike antigenic sequences and augment CD8 cells reactive to the S1 spike sequence, which is more specific for the SARS-CoV-2 virus. In this exploratory cohort of vaccinated immunocompromised subjects, S1-reactive CD8 cells can be detected in some who are negative for RBD antibody, and S-reactive T-cells are present in all who are negative for spike antibody. |
