CirculatingMycoplasma hyopneumoniae-specific cytokine producing T-cell subsets and IFN-γ production in blood of sows. A–D Circulating Mycoplasma hyopneumoniae-specific cytokine producing T-cell subsets in blood of sows; E average IFN-γ production by the different T-cell subsets. PBMCs were stimulated with M. hyopneumoniae J strain bacterin and T-cell phenotype and cytokine production were assessed by flow cytometry. Farm A: endemically infected with M. hyopneumoniae; Farm B: free of M. hyopneumoniae. On farm A, sows (n = 6) were vaccinated against M. hyopneumoniae at 6 and 3 weeks before farrowing, blood samples were taken before the first vaccination (pre vacc.) and at the time of farrowing (post vacc.), on farm B blood was sampled of the sows (n = 3) at the time of farrowing. *, P < 0.05 between pre- and post-vaccination on farm A; **, P < 0.05 between farm A and B.