The threshold at which antigen triggers lymphocyte activation is set by the enzymes that regulate tyrosine phosphorylation. Upon T cell activation, the protein tyrosine phosphatase SHP-1 was found to bind to the protein tyrosine kinase ZAP-70. This interaction resulted in an increase in SHP-1 phosphatase activity and a decrease in ZAP-70 kinase activity. Expression of a dominant negative mutant of SHP-1 in T cells increased the sensitivity of the antigen receptor. Thus, SHP-1 functions as a negative regulator of the T cell antigen receptor and in setting the threshold of activation.

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Probiotics might ameliorate the dysbiosis of CF gut microbiota, characterized by a high density of Proteobacterial organisms. L. reuteri significantly decrease intestinal inflammation and increase digestive comfort.

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Intestinal intraepithelial lymphocytes (i-IEL) represent one of the largest, non-organized lymphoid population in the body. They are located outside the epithelial basement membrane among the mucosal epithelial cells. We, and previously other groups, have reported the presence of a CD7+CD3-IEL subset in the epithelium of human small intestine. This subset is drastically reduced in coeliac disease (CD) patients. In the present work we accomplish a better phenotypic characterization of this CD3-IEL subset and demonstrate the expression of typical natural killer (NK) cell markers. Most, if not all, CD3-CD7+ cells express NKPR1 (CD161)[98% +/- 2] and CD122[92% +/- 6]. In addition, a variable percentage express CD2[55% +/- 16], CD94[24% +/- 18], CD56[44% +/- 21] and CD16[12% +/- 4], however, no CD57 expression was observed. Moreover, these cells contain perforin granules[75% +/- 5], supporting a potential cytolytic ability. Regarding adhesion molecules, CD18 and CD44 expression is absent, which is consistent with a limited capacity of migration. Altogether, these data suggest the presence of intraepithelial NK cells in human intestinal epithelium, a compartment where cytotoxic effectors have not been clearly defined.

Changes in T cell receptor gammadelta and CD3-/CD7+ intraepithelial lymphocytes subsets are permanently observed in paediatric coeliac disease. Their assessment, by three-colour flow cytometry on routine diagnostic biopsies, permits a better characterization of coeliac enteropathy and represents a valuable procedure to identify coeliac patients with different clinical presentations.