Quantitative and functional characteristics of intestinal-homing memory T cells: analysis of Crohn's disease patients and healthy controls

Abstract

SUMMARY Circulating memory T cells can be subdivided on the basis of β7 integrin expression. The β7+ population contains cells primed in the intestine capable of homing back to the gut. We hypothesized that cytokine production by β7+ memory T cells reflects the specialized mucosal compartment in which they were primed. Flow cytometry of whole blood was used to assess numbers of β7+ (β7hi and β7int) and β7– memory T cells and their production of Th1 and regulatory cytokines in healthy controls and Crohn's disease patients. In controls, β7+ and β7– memory T cells displayed a similar qualitative profile of cytokine production but the β7+ population was enriched for cytokine-producing effector cells. In addition, the β7hi population contained more cytokine-producing cells than the β7int population, suggesting a gradient of cytokine production based on β7 integrin expression. In active Crohn's disease, there was altered expression of β7 integrin with a decrease in intestinal-homing memory T cells and an increase in systemic memory T cells. Furthermore, there was a selective loss of IL-10 and increase in TGF-β in both β7+ and β7– memory T cell subsets which may contribute to the pathogenesis of the inflammatory process in Crohn's disease.