T helper I-type immune reactions in the gut cause important human diseases,
such as Crohn's disease and coeliac disease. Here, Tom MacDonald, Mona Ell
iott and Sylvia Pender suggest that the tissue injury in these diseases is
mediated not by the immune cells, but by cytokine-induced changes in kerati
nocyte growth fact or and matrix metalloproteinase production by resident g
ut myofibroblasts.