Characterization of main cytokine sources from the innate and adaptive immune responses following primary 17DD yellow fever vaccination in adults

The mechanisms of immune response following yellow fever (YF-17DD) vaccination are still poorly understood. In this study, we have performed a longitudinal investigation (days 0, 7, 15 and 30) to characterize the cytokine profile of innate and adaptive immunity following YF-17DD first-time vaccination. Data from non-stimulated cultures demonstrated a prominent participation of the innate immunity with increased frequency of TNF-α+ neutrophils and IFN-γ+ NK-cells at day 7 besides TNF-α+ monocytes at day 7, day 15 and day 30. Increased frequency of IL-10+ monocytes was observed at day 15 and day 30, and decreased percentage of IL-4+ NK-cells were detected at day 7, day 15 and day 30. Time-dependent and oscillating cytokine pattern was observed in CD4+ T-cells, with low percentage of IL-12+, IL-4+ and IL-10+ cells at day 7 and increased frequency of TNF-α+ cells at day 15 besides IFN-γ+ and IL-5+ cells at day 15 and day 30. Later changes with increased percentage of IL-12+ and IL-5+CD8+ T-cells were observed at day 30. Increased frequency of IL-10+ B-cells was observed at day 15, when seroconversion was detected in all vaccinees. The overall cytokine analysis of non-stimulated leukocytes showed a transient shift towards a pro-inflammatory profile at day 7, mainly due to changes in the innate immunity, which draws back toward a mixed/regulatory pattern at day 15 and day 30. The changes induced by the in vitro YF-17DD vaccine-stimulation were mainly observed at day 0 and day 7 (before seroconversion) with minor changes at day 15 and day 30 (after seroconversion). These data support the hypothesis that a complex network with mixed pro/anti-inflammatory cytokine profile is associated with the establishment of the protective immunity following YF-17DD primo-vaccination, free of adverse events.