Characterization of Th17 responses to Streptococcus pneumoniae in humans: Comparisons between adults and children in a developed and a developing country

► Memory IL-17A and IL-22 responses to pneumococcal antigens demonstrated in humans. ► Separate subsets of CD4+ T cells produce IL-17A and IL-22. ► Stronger Th17 responses in adults compared to children in Sweden. ► Strong and comparable Th17 responses in children and adults in Bangladesh. ► Exposure likely determines Th17 responses, important for future vaccine research.