Dietary RNA (s. Cerevisiae) stimulated cytokine secretion in human immune cells: involvement of p38 MAPK, and co-stimulation with LPS or PHA

Abstract

Dietary nucleotides and nucleic acids are known to affect immune functions in animals and humans, both in vitro and in vivo. In this thesis I wanted to investigate the effect of dietary RNA from baker’s yeast on cytokine secretion from human peripheral blood mononuclear cells (PBMS). We co‐cultured PBMCs from 11 subjects with RNA, LPS, PHA, SB 202190 and combinations of these, and analyzed supernatants for cytokines using ELISA kits. RNA induced secretion of IL‐1α, IL‐1β, IL‐6, IL‐8, IL‐10, TNF‐α and GM‐CSF, co‐stimulation of RNA increased secretion in PHA stimulated GM‐CSF only. No secretion of IL‐2, IL‐4, IL‐12 or IL‐17α was detected. Inhibition of p38 MAPK with SB 202190 decreased RNA especially, but also LPS and PHA induced cytokine secretions. These results indicate that RNA induce cytokine secretion alone, but has little additive effect on secretion by LPS and PHA stimulation, except for GM‐CSF; and the effect of RNA is partly mediated by p38 MAPK. The stimulatory effect on GM‐CSF might indicate a role for RNA in priming of innate immune response.