Vitamin D and vitamin D receptor (VDR) deficiency results in severe symptoms of experimental inflammatory bowel disease in several different models. The intraepithelial lymphocytes of the small intestine contain large numbers of CD8αα(+) T cells that have been shown to suppress the immune response to Ags found there. In this study, we determined the role of the VDR in the development of CD8αα(+...

Most gut intraepithelial cells (IEL) of the mouse are T cells that bear CD8 molecules, present either as alpha-beta chain heterodimers (CD8 beta+) or as alpha chain homodimers (CD8 beta-). All CD8 beta+ IEL bear alpha/beta T cell receptors (TCR); CD8 beta- IEL bear either alpha/beta or gamma/delta TCR and are considered to be a thymus-independent (TI) population, probably arising locally from a...

Positive selection of CD4+CD8+ T cells to the CD4+CD8- helper and CD4- CD8+ cytotoxic lineages is a multistep process that involves complex regulation of coreceptor gene expression. By analyzing expression of a reporter gene in transgenic mice, we have identified a DNA segment, located between the murine CD8beta and CD8alpha genes, that has enhancer activity restricted to CD8 lineage cells. Rem...

As a sensor of polyaromatic chemicals the aryl hydrocarbon receptor (AhR) exerts an important role in immune regulation besides its requirement for xenobiotic metabolism. Transcriptional activation of AhR target genes is counterregulated by the AhR repressor (AhRR) but the exact function of the AhRR in vivo is currently unknown. We here show that the AhRR is predominantly expressed in immune ce...

The cellular infiltrate of the jejunal mucosa has been studied in patients with both treated and untreated adult coeliac disease and dermatitis herpetiformis and serially in treated patients before and after the reintroduction of gluten to the diet. In adult coeliac disease and dermatitis herpetiformis the jejunal mucosa showed similar abnormalities of the cellular infiltrate which was characte...

The aims of this study were first, to assess whether or not immunoglobulin secretion from human gut mucosal B lymphocytes can be modified by T lymphocytes, and second whether human gut mucosal T lymphocytes are capable of regulating mucosal B lymphocyte function. T and B lymphocyte enriched cell populations were isolated from gut mucosa and co-cultured in varying proportions. Addition of T lymp...

Mouse gut intraepithelial lymphocytes (IEL) consist mainly (90%) of two populations of CD8+ T cells. One bears heterodimeric alpha/beta CD8 chains (Lyt-2+, Lyt-3+), a T cell receptor (TCR) made of alpha/beta chains, and is Thy-1+; it represents the progeny of T blasts elicited in Peyer's patches by antigenic stimulation. The other bears homodimeric alpha/alpha CD8+ chains, contains no beta chai...

A 74-year-old male with a history of dysphagia for 3 years presented with acute food impaction. Endoscopy showed a tight distal stricture with course rings at the middle third of the esophagus. Biopsies taken from the middle third of the esophagus showed marked infiltration of the intraepithelial lymphocytes mainly in a peripapillary distribution. The immunostains showed presence of CD3 and CD5...

Expression of the BY55 protein has been shown to be tightly associated with NK and CD8+ T lymphocytes with cytolytic effector activity. To determine the function of this protein, we molecularly cloned BY55 cDNA. The cDNA sequence predicts a cysteine-rich, glycosylphosphatidylinositol-anchored protein of 181 amino acids with a single Ig-like domain weakly homologous to killer inhibitory receptor...