Background The pathogenesis of PFAPA syndrome is unknown. According to Stojanov et al. cytokine profile in PFAPA syndrome suggests Th1 mediated inflammatory process resulting in continuous inflammation and reduced Th2 anti-inflammatory response. Interferon γ might be responsible for suppressing the production of IL-4 and IL10. Hung et al. showed suppressive effects of ketotifen on the expression of Th1 and Th2 related chemokines of human monocytes.

The aim of this study was to assess autoimmune response following annual influenza vaccination in apparently healthy adults, staff at a children's hospital. 92 healthy adult subjects were tested for autoantibodies including antinuclear antibodies (ANA), anti-extractable nuclear antigen antibodies (anti-ENA), antiphospholipid antibodies (aPL), namely anticardiolipin antibodies (aCL), anti-beta2-glycoprotein I antibodies (aβ2-GPI) and lupus anticoagulant (LA). Blood samples were taken from each participant before annual influenza vaccination, one month and six months after vaccination. Before influenza vaccination 26% of participants were positive for ANA, 1% for anti-ENA, 16% for aCL, 7% for aβ2-GPI and 2% for LA. One month after influenza vaccination 76% of participants showed no change in autoantibodies titres. Six months after influenza vaccination 74% of participants showed no change in autoantibodies titres. Overall, there was no statistically significant difference in the percentage of positive ANA, aCL, aβ2-GPI and LA before and 6 months after the vaccination. Five participants developed autoantibodies 6 months after the vaccination and one who was initially low positive for ANA became highly positive (1:320). Eleven participants had only transiently increased autoantibodies. Persistently positive or progressively increased levels of autoantibodies during 6 months' follow up were observed in 6 persons (7%). Our study showed a high percentage of positive autoantibody testing among healthy adult staff at a children's hospital. There was no statistically significant difference in the percentage of positive autoantibodies before and after influenza vaccination. However, our study clearly demonstrated induction of autoantibodies production in selected subjects.