RESUMO
BACKGROUND: The live attenuated yellow fever (YF) vaccines have been available for decades and are considered highly effective and one of the safest vaccines worldwide. METHODS: The impact of YF-17DD-antigens recall on cytokine profiles of YF-17DD-vaccinated children were characterized using short-term cultures of whole blood samples and single-cell flow cytometry. This study enrolled seroconverters and nonseroconverters after primovaccination (PV-PRNT⺠and PV-PRNTâ»), seroconverters after revaccination (RV-PRNTâº), and unvaccinated volunteers (UV-PRNTâ»). RESULTS: The analysis demonstrated in the PV-PRNT⺠group a balanced involvement of pro-inflammatory/regulatory adaptive immunity with a prominent participation of innate immunity pro-inflammatory events (IL-12⺠and TNF-α⺠NEU and MON). Using the PV-PRNT⺠cytokine signature as a reference profile, PV-PRNTâ» presented a striking lack of innate immunity proinflammatory response along with an increased adaptive regulatory profile (IL-4âºCD4⺠T cells and IL-10⺠and IL-5âºCD8⺠T cells). Conversely, the RV-PRNT⺠shifted the overall cytokine signatures toward an innate immunity pro-inflammatory profile and restored the adaptive regulatory response. CONCLUSIONS: The data demonstrated that the overall cytokine signature was associated with the levels of PRNT antibodies with a balanced innate/adaptive immunity with proinflammatory/regulatory profile as the hallmark of PV-PRNT(MEDIUMâº), whereas a polarized regulatory response was observed in PV-PRNTâ» and a prominent proinflammatory signature was the characteristic of PV-PRNT(HIGHâº).