Abstract:
COVID-19 is a disease that began in the city of Wuhan, China, and quickly spread
across the world, leading the World Health Organization to declare a pandemic in
March 2020. Due to the high number of deaths caused by the disease, scientific
advancements in the search for prevention and treatment methods against SARS
CoV-2 led to the development of different vaccine platforms. Research evaluating
the efficacy of vaccines after immunization showed varying results regarding the
immune response induced by vaccination, due to the different vaccines available.
Therefore, understanding more about the cellular immune response under different
protocols is important to better comprehend the vaccine-induced response. Our
objective in this study was to evaluate the profile of memory T and B lymphocytes
and follicular T cells in individuals vaccinated against COVID-19. We collected
peripheral blood samples from 12 vaccinated individuals, separated mononuclear
cells, cultured them with the SARS-CoV-2 RBD antigen, and analyzed the memory
T and B lymphocytes and follicular T cells using flow cytometry. Additionally, levels
of IFN-γ and IL-10 in the culture supernatants were measured by ELISA. As a result,
we found higher frequencies of EMRA and EM T cells in vaccinated participants and
across subgroups (homologous, heterologous, 3 and 4 doses). We observed
increased expression of IFN-γ and TGF-β by EM T cells, as well as higher levels of
IL-10 and IFN-γ in the supernatants of stimulated cultures from vaccinated
participants. Our results suggest that, regardless of the vaccination protocol, the
immune response is similar and effective.
