Kinetics of cytokine expression in bovine PBMCs and whole blood after in vitro stimulation with foot-and-mouth disease virus (FMDV) antigen

• FMDV antigen induces recall cytokine responses in bovine blood cells.
• mRNA induction peaked at 6 h for IL-2 and IFN-γ, and 24 h for IL-4 in PBMCs.
• Protein level peaked at 72 h for IL-2 and IL-4, and 96 h for IFN-γ in whole blood.

The interest in analysing antigen-specific cytokine responses has substantially increased in recent years, in part due to their use in assessing vaccine efficacy. In the present study, the kinetics of IL-2, IL-4 and IFN-γ expression was determined in bovine PBMCs by real-time PCR and in whole blood by cytokine-release assay after in vitro stimulation with recall foot-and-mouth disease virus (FMDV) antigen. The results showed that the cytokine mRNA of IL-2 and IFN-γ in PBMCs were induced early (peak induction at 6 h), whereas the IL-4 mRNA showed delayed induction (peaked at 24 h). In contrast, the kinetics of cytokine proteins in whole blood was different and required the accumulation of the proteins before being optimally detected. The peak accumulation of cytokine protein in whole blood was recorded at 72 h for IL-2 and IL-4, and 96 h for IFN-γ. The findings of this study are of importance when selecting an optimal time points for measuring antigen-specific cytokine expression in cattle.