Impaired interleukin ‐4 signalling promotes establishment of Haemonchus contortus in sheep

SummaryReduced worm burden in St. Croix (STC) sheep duringHaemonchus contortus (Hc) infection is predicated on rapid interleukin ‐4 (IL‐4) signalling and T helper type 2 immune (Th2) response. The aim of these studies was to further elucidate differences in Th2 responses by STC and Suffolk (SUF) sheep. Ten days after challenge Hc infection, peripheral blood mononuclear cells (PBMC) were collected and cultured with larval (HcLA) and adult worm (HcWA) antigen. STC PBMC produced nearly twice as much IL‐4 as SUF (823.57 pg/mL vs 454.28 pg/mL) at 6 hours of HcLA culture despite no difference inIL ‐4 gene expression and the IL ‐4 receptor (IL4Rα) was upregulated in STC PBMC but was undetectable in SUF. Expression of other Th2‐type genes were increased in STC PBMC includingIL13, IL5 andMRC1. IL ‐4 supplementation to HcLA culture was insufficient to achieve upregulation of Th2 genes in SUF PBMC. Production of IL‐4 did not occur in SUF PBMC until 24 hours after culture with HcLA, and expression ofIL4 in the abomasum was similarly delayed until 10  days after challenge infection, which was associated with significantly higher larval burden (530 vs 16). These data demonstrate delayed upregulation of Th2 genes in SUF sheep contributes to susceptibility to Hc.
Source: Parasite Immunology - Category: Parasitology Authors: Tags: ORIGINAL ARTICLE Source Type: research