Interleukin-6 expression in gut of parasite challenged sheep

Following challenge with Trichosirongylus colubrifonizis, increased numbers of T-cells and immunoglobulin responses are seen in the intestine of sheep immunised by repeated infection with live worms. IL-6 mRNA expression in the small intestine from T. colubriformis-immunised and naive sheep was determined by in situ hybridisation, whereas CD4+, IgA+, IgG+ cells in the gut were evaluated by immunohistochemistry. There was constitutive expression of IL-6 mRNA by cells in the naive gut, and the number of these cells was increased by parasite challenge. There were corresponding increases in numbers of CD4+ and TCRγ/δ+ T-cells and IgG+ B-cells. Our data are consistent with a role for IL-6, perhaps produced by CD4+ and/or TCRγ/δ+ T-cells or B-cells, in B-cell terminal differentiation. Infiltration of B-cells, particularly IgG+ B-cells, may reflect parasite immunity in the host.