Expression of T cell receptors αβ and γδ in the ileal mucosa of patients with Crohn's disease and with spondylarthropathy

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Abstract
The expression of the αβ and γδ heterodimer of the T cell receptor (TCR) was studied in normal human ileal mucosa or in ileal biopsies featuring Crohn's disease or acute and chronic spondylarthopathy-related gut inflammation. With an immunohistochemical technique we demonstrated that the increase of mucosal lymphocytes per mm mucosa in Crohn's disease and spondylarthropathy-related ileitis is exclusively due to expansion of the αβ+ T cell compartment. In Crohn's disease and chronic ileitis observed in some spondylarthropathy patients the αβ+ T cells were increased amongst intraepithelial lymphocytes (IEL). The lamina propria lymphocytes (LPL) were augmented in all studied inflammatory conditions. The γδ+ T cells showed no changes in IEL or LPL and their proportions were not altered. They were evenly dispersed throughout the ileal mucosa and did not seem to participate in the inflammatory process. This study confirms that γδ T cells are a distinct subset in the intestinal mucosa. The increase in αβ+ T cells suggests augmented mucosal antigen handling and involvement of the major histocompatibility complex in the pathogenesis of spondylarthropathy-related gut inflammation and Crohn's disease.