Superantigenic Staphylococcus aureus stimulates production of interleukin-17 from memory but not naive T cells.

T-helper 17 (Th17) cells are characterized by their production of interleukin-17 (IL-17) and have a role in the protection against infections and in certain inflammatory diseases. Humans who lack Th17 cells are more susceptible to Staphylococcus aureus infections compared to individuals having Th17 cells. S. aureus is part of the commensal skin microflora and also colonize the infant gut. To investigate whether UV-killed S. aureus would be more capable of inducing IL-17 than other commensal bacteria, we stimulated mononuclear cells from adults, infants, and newborns with various gram-positive and gram-negative commensal bacteria. IL-17 was produced from adult memory Th17 cells after stimulation with superantigen-producing S. aureus but not nonsuperantigenic S. aureus or other common commensal gut bacteria. Cells from newborns were poor IL-17 producers after stimulation with S. aureus, whereas in some cases IL-17 was secreted from cells isolated from infants at the age of 4 and 18 months. These results suggest that superantigenic S. aureus are particularly efficient in stimulating IL-17 production and that the cytokine is produced from memory T cells.