Recognition of the antigen-presenting molecule MR1 by a Vδ3+ γδ T cell receptor

Unlike conventional αβ T cells, γδ T cells typically recognize nonpeptide ligands independently of major histocompatibility complex (MHC) restriction. Accordingly, the γδ T cell receptor (TCR) can potentially recognize a wide array of ligands; however, few ligands have been described to date. While there is a growing appreciation of the molecular bases underpinning variable (V)δ1+ and Vδ2+ γδ TCR-mediated ligand recognition, the mode of Vδ3+ TCR ligand engagement is unknown. MHC class I–related protein, MR1, presents vitamin B metabolites to αβ T cells known as mucosal-associated invariant T cells, diverse MR1-restricted T cells, and a subset of human γδ T cells. Here, we identify Vδ1/2− γδ T cells in the blood and duodenal biopsy specimens of children that showed metabolite-independent binding of MR1 tetramers. Characterization of one Vδ3Vγ8 TCR clone showed MR1 reactivity was independent of the presented antigen. Determination of two Vδ3Vγ8 TCR-MR1-antigen complex structures revealed a recognition mechanism by the Vδ3 TCR chain that mediated specific contacts to the side of the MR1 antigen-binding groove, representing a previously uncharacterized MR1 docking topology. The binding of the Vδ3+ TCR to MR1 did not involve contacts with the presented antigen, providing a basis for understanding its inherent MR1 autoreactivity. We provide molecular insight into antigen-independent recognition of MR1 by a Vδ3+ γδ TCR that strengthens an emerging paradigm of antibody-like ligand engagement by γδ TCRs.

Novel fluorescent biosensor for carcinoembryonic antigen determination via atom transfer radical polymerization with a macroinitiator

A novel fluorescence method for CEA via β-CD and BIBB-initiated atom transfer radical polymerization (ATRP) was reported.

AGE FEATURES OF INTESTINAL AMOEBIASIS

Study objective. To establish clinical and epidemiological features of intestinal amebiasis in adults and children at the present stage. A retrospective analysis of patient histories of 90 cases of intestinal amebiasisin patients aged 3 to 40 years who were on inpatient treatment in Regional Infectious Clinical Hospital named after A.M Nichogi, Astrakhan, in the period from 2014 to 2017. The diagnosis of amebiasis was confirmed by microscopy of feces, detection of antibodies by using reaction of indirect hemagglutination (RHAG) with a specific antigen, determination of DNA of the parasite by polymerase chain reaction (PCR).Results. It was determined that the incidence of intestinal amebiasis in the Astrakhan region is sporadic with the involvement in the epidemic process of persons of working age from 18 to 40 years (75.6%) and children aged 3 to 10 years (24.6%) of organized groups living in the city. Acute intestinal amebiasis in 86.8% of adults proceeded in mild to moderate form. The clinical course of the disease was characterized by a gradual onset in 82.4%, mucosal-bloody stool in 94.1%, the outcome of a chronic recurrent form in 11.8%. Raspberry jelly-like stool, extraintestinal complications of amebiasis, characteristic of amebiasis of previous years, were absent.The features of intestinal amebiasis in children were: acute onset of the disease in 63.6%, fever 38°C and above in 54.5%, abdominal pain in 95.5%, prolonged diarrhoea with a stool frequency of more than 10 times in 72.7%, stool with blood mucus in 95.5%, tenesmus in 36.4%, dehydration in 18.6% of patients. The mild form of the disease in children was not observed, severe was observed in 54.5%, moderate in 45.5%. The combined course of intestinal amebiasis with bacterial dysentery, proceeded more severely, changed clinical symptoms of the disease, made it difficult to diagnose amebiasis in a timely manner.