Surface Of Immunocompetent Cells Research Articles

Sepsis Course and Outcome Depends on the Genetic Variant in the 3`-Region of Aquaporin 4 Gene <i>AQP4</i> and Comorbidities

Aquaporins 4 and 5 are proteins that form water channels in the cell membrane, participate in the transfer and migration of immune cells, being expressed on many cell types including CNS astrocytes, kidney cells, lungs, and the immune system. We have previously shown that AQP5 genetic polymorphism is associated with different outcomes of abdominal sepsis. Since another common aquaporin protein, AQP4, is also expressed on the surface of immunocompetent cells, determining cell motility, it was suggested that AQP4 may also be important in the pathogenesis of sepsis, and that AQP4 polymorphism may predetermine sepsis severity and outcome. AQP4 rs1058427 genetic polymorphism has not been studied earlier. The aim of the study was to determine the effects of region 3` polymorphism in the AQP4 gene on the clinical course and outcome of sepsis.Materials and methods. The prospective study included 290 ICU patients from three clinical hospitals in Moscow aged 18–75 years with clinical signs of sepsis (SEPSIS-3, 2016).Results. It was found that the minor T allele of the AQP4 rs1058427 gene provides strong protection against septic shock, as among GG genotype carriers septic shock developed in 66%, but in presence of the minor T allele dropped to half of cases (P=0.009, Fisher’s exact test, OR=1.99, 95% CI: 1.12–3.55, N=290). There was a significant association between AQP4 rs1058427 genetic polymorphism and 30-day hospital mortality in a subgroup of patients with more severe organ dysfunction and higher comorbidity burden (cardiovascular diseases, type II diabetes mellitus) requiring extracorporeal treatment modalities and ventilator support for 5 or more days (N=66). Carriers of the minor T allele showed better survival rates as compared AQP4 rs1058427 GG genotype carriers (5 deaths out of 10 and 47 deaths out of 56, respectively, P=0.003, Fisher’s exact test, N=66, OR=5.22, 95% CI: 1.25–21.82, P=0.009, log-rank criterion).Conclusion. The minor AQP4 rs1058427 T allele is associated with protection against septic shock and better survival in sepsis in a group of ICU patients with high comorbidity burden requiring extracorporeal life support interventions.

Fluorescent Methods in the Study of UV-Induced Changes in Structural and Functional State of Human Blood Lymphocytes

Structural and functional state of human blood lymphocytes after exposure to UV light (240-390 nm) in doses of 151-1359 J/m(2) was studied by methods of laser flow cytofluorometry, indirect immunofluorescence, and fluorescent probes. Using a combination of these methods, we have showed that UV light in the specified doses induced changes in the surface phenotype of T cells: stimulation or suppression of the expression of antigen-recognizing receptor complex molecules (CD3, CD4, and CD8 markers) and their redistribution on the surface of immunocompetent cells (capping effect) with the formation of receptor clusters of various types.

Risk of Diabetic Nephropathy in Type 1 Diabetes Is Associated With Functional Polymorphisms in RANTES Receptor Gene (CCR5)

Chemokines and their receptors have been implicated in the development of diabetic nephropathy. To determine whether the risk of diabetic nephropathy is influenced by two functional polymorphisms in the regulated upon activation normal T-cell expressed and secreted (RANTES) receptor gene (CCR5), we recruited patients with type 1 diabetes, including 496 case subjects with overt proteinuria or end-stage renal disease and 298 control subjects with normoalbuminuria. Male carriers of the 59029G allele, which is associated with diminished expression of CCR5 on the surface of immunocompetent cells, had significantly higher risk of developing diabetic nephropathy than noncarriers (OR [95% CI] 1.9 [1.2-3.0]). Similarly, male carriers of the 32-bp deletion, which causes truncation of the protein, had significantly higher risk of diabetic nephropathy than noncarriers (2.3 [1.3-4.2]). Combining both polymorphisms, three haplotypes were distinguished: one nonrisk haplotype carrying the 59029A allele and the 32-bp insertion and two risk haplotypes carrying the 59029A allele with the 32-bp deletion and carrying the 59029G allele with the 32-bp insertion. The distribution of these haplotypes differed significantly (P < 0.00001) in men with and without diabetic nephropathy but was not associated with diabetic nephropathy in women. In conclusion, two functional polymorphisms in CCR5 that decrease expression of the RANTES receptor on immunocompetent cells are associated with increased risk of diabetic nephropathy in type 1 diabetes, but only in men.

Expression and transcriptional regulation of the human alpha3 neuronal nicotinic receptor subunit in T lymphocyte cell lines.

The expression of neurotransmitter receptors on the surface of immunocompetent cells is generally accepted as evidence that the nervous system can influence immune responses, even though many aspects of these interactions remain to be elucidated. In this article, we analyzed the expression of the alpha3 nicotinic receptor subunit in human cell lines of myeloid and lymphoid origin and show that the alpha3 mRNA and the receptor molecules containing this subunit are specifically expressed in T lymphocyte cell lines. We have previously characterized the structural properties of the human alpha3 nicotinic subunit gene promoter and defined its functional profile in neuronal cells; in this study, we analyzed the activity of the alpha3 promoter in T lymphocytes and found that the same minimal promoter located in the 0.16-kb BglII-AccIII fragment is responsible for the expression of the alpha3 mRNA in both neuronal and T lymphocyte cell lines. However, the alpha3 transcription initiation patterns in the two cell types were both qualitatively and quantitatively different, and the minimal promoter was differentially modulated by downstream and upstream regulatory elements. These findings suggest that distinct transcriptional mechanisms allow the same promoter to be regulated in a tissue-specific fashion, according to the different functional needs of the two cell types.

Effect of UVB radiation on the biosynthesis of HLA-DR antigens

HLA-DR molecules on the surface of immunocompetent cells are thought to represent target structures for the immunomodulating effects of UV radiation during the induction of an immune response. We therefore investigated the effect of UVB radiation on the de novo synthesis of HLA-DR-gamma-chains in the cytoplasm and the expression of alpha- and beta-chains on the surface of the human lymphoblastoid B-cell line Raji. Raji cells were UVB irradiated before biochemical experiments were performed. Cells were then metabolically labeled or radioiodinated and detergent lysates immunoprecipitated using antibodies directed against the gamma- or the alpha- and beta-chain of the HLA-DR molecule. Over a wide dose range, UVB-irradiated Raji cells were shown to still express HLA-DR determinants on their surface and, even more importantly, to be capable of synthesizing HLA-DR-alpha, beta- and gamma-chains in a normal fashion. Despite this, the functional capacity of Raji cells was impaired in a dose-dependent manner. UV radiation thus seems to exert its immunomodulating effects primarily at a different level than the incriminated immune-response-associated antigens, which are expressed as recognition structures on the surface of immunocompetent cells.

Complete characterization and sequence of an HLA class II DR beta chain cDNA from the DR5 haplotype.

The human major histocompatibility complex includes the DP, DQ, and DR subregions, each of which contains at least one alpha chain gene and two beta chain genes. The products of the alpha chain gene and a beta chain gene from a given subregion combine to form a heterodimer which is found predominantly on the surface of immunocompetent cells, and is essential for effective cell-cell interactions and the generation of an immune response. The beta chain of the DR molecule is highly polymorphic, and it is this polymorphism which is thought to be ultimately responsible for the specific immune responsiveness and disease predisposition conferred by different DR molecules. While the sequences of DR beta chains of the homozygous DR1 cells, homozygous DR2, homozygous DR4, DR3/w6 cells and DR4/w6 genotypes have been partially or completely characterized, no sequence is yet available for the DR beta chain from a homozygous DR5 cell. A cDNA library was therefore constructed from the Swei cell line homozygous for the DR5 haplotype. A beta chain clone was isolated, characterized, and sequenced. Comparison with previously published DR beta chain restriction endonuclease maps and nucleotide sequences demonstrated that this clone was a DR beta chain clone. Comparison of the deduced amino acid sequence with other DR beta chain amino acid sequences shows three regions of variability in the first external domain, corresponding to amino acid residues 9-13, 26-38, and 67-74. The sequence of each of these variable regions in the beta chain from DR5 cells was identical or nearly identical to the sequences of variable regions found in the beta chains of other DR haplotypes, supporting the notion of gene conversion as an evolutionary mechanism generating polymorphism. The second external domain, and transmembrane and intracytoplasmic regions show a high degree of sequence conservation.

A molecular basis for the Ia.2 and Ia.19 antigenic determinants.

The murine Ia antigens, heterodimeric glycoproteins on the surface of immunocompetent cells, restrict immune recognition by their influence on cell-cell interactions. Many serological specificities have been mapped to these molecules, and monoclonal antibodies directed against some of these determinants block antigen presentation to T lymphocytes. As a step toward a better understanding of Ia function, we sought to define the molecular basis of Ia.2 and Ia.19, specificities found on the A alpha chain of only the k or of both k and r haplotypes, respectively. We report nucleotide sequences for the A alpha chain cDNAs of the k, r, and s haplotypes, which, when compared to previously published A alpha sequences, demonstrate the existence of one k-specific amino acid residue and of another present only in the k and r haplotypes. These residues must thus play an important role in the generation of Ia.2 and Ia.19 specificities.

Functional expression of HLA-DP genes transfected into mouse fibroblasts.

The HLA class II antigens are a highly polymorphic family of dimeric cell-surface glycoproteins, expressed predominantly on the surface of immunocompetent cells. They are intimately involved with the induction of the T-cell response to extrinsic antigen and are important predisposing factors for a wide spectrum of autoimmune diseases. We describe here the expression of a class II product from the HLA-DP (new WHO nomenclature, formerly SB) subregion after transfer of cloned genes into mouse fibroblasts. The transfected DP antigen is recognized by several HLA class II monoclonal antibodies and, though present in a mouse cell background, is able to function in the presentation of influenza antigen to cloned DP-restricted human T lymphocytes.