Chicken IL-17F: identification and comparative expression analysis in Eimeria-infected chickens.

Interleukin-17F (IL-17F) is a proinflammatory cytokine, which plays an important role in gut homeostasis. A full-length chicken IL-17F (chIL-17F) cDNA with a 510-bp coding region was identified from ConA-activated chicken splenic lymphocytes. ChIL-17F shares 53% amino acid sequence identity with the previously described chicken IL-17 (chIL-17A) and 38-43% with mammalian homologues. The locus harboring chIL-17 and chIL-17F displayed inverted order compared to those of mammals. ChIL-17F transcript expression was high in lymphoblast cell line CU205 and at moderate levels in small and large intestines and liver. ChIL-17F and chIL-17 expression profiles were examined by quantitative real-time RT-PCR in mitogen-stimulated splenic lymphocytes and intestinal areas affected by Eimeria maxima and Eimeria tenella infections. Expression levels of chIL-17F, like chIL-17, were elevated in mitogen-activated splenic lymphocytes. ChIL-17F, but not chIL-17, expression was upregulated in intestinal tissues affected by E. maxima and E. tenella infections. Recombinant chIL-17F biological activities were similar to that of chIL-17 in primary chicken embryonic fibroblasts. These results suggest that chIL-17F is a unique member of the IL-17 family of cytokines.