Expansion of Parasite-Specific CD4+ and CD8+ T Cells Expressing IL-10 Superfamily Cytokine Members and Their Regulation in Human Lymphatic Filariasis

Background:lymphatic filariasis (lf) is known to be associated with an increased production of il-10. the role of the other il-10 family members in the pathogenesis of infection and/or disease is not known.methodology/principal findings:we examined the expression patterns of il-10 family members - il-19,il-24 and il-26 in lf. we demonstrate that both cd4+ and cd8+ t cells express il-19,il-24 and il-26 and that the frequency of cd4+ t cells expressing il-19 and il-24 (as well as il-10) is significantly increased at baseline and following filarial antigen stimulation in patients with lf in comparison to individuals with filarial lymphedema and uninfected individuals. this cd4+ t cell expression pattern was associated with increased production of il-19 and il-24 by filarial - antigen stimulated pbmc. moreover,the frequency of cd4+ and cd8+ t cells expressing il-26 was significantly increased following filarial antigen stimulation in filarial lymphedema individuals. interestingly,il-10 blockade resulted in diminished frequencies of il-19+ and il-24+ t cells,whereas the addition of recombinant il-10 resulted in significantly increased frequency of il-19+ and il-24+ t cells as well as significantly up regulated il-19 and il-24 gene expression,suggesting that il-10 regulates il-19 and il-24 expression in t cells. in addition,il-1β and il-23 blockade also induced a diminution in the frequency of il-19+ and il-24+ t cells,indicating a novel role for these cytokines in the induction of il-19 and il-24 expressing t cells. finally,elimination of infection resulted in significantly decreased frequencies of antigen - specific cd4+ t cells expressing il-10,il-19 and il-24.conclusions:our findings,therefore,suggest that il-19 and il-24 are associated with the regulation of immune responses in active filarial infection and potentially with protection against development of pathology,while il-26 is predominantly associated with pathology in lf. © 2014.