Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0033036 (APC)
 10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In addition to polymorphism of the peptide-binding site, the density of the MHC class II molecules expressed on the membrane of APC could well play a significant role in the MHC-peptide-TCR interaction during the immune response. We therefore investigated the regulation of the expression of the HLA-DRB genes at the transcriptional level. A competitive PCR approach was used to estimate the quantities of the HLA-DRB transcripts in peripheral blood B cells. When comparing the amounts of steady-state mRNAs among the different DRB1 alleles, the DRB1 transcripts in the DR52 haplotype group were found to be 2.5 to 3.5 times more abundant than the DRB1*01 transcripts, 1.5 to 2 times more abundant than the DRB1*04 transcripts, and 7 times more abundant than the DRB1*08 transcripts. Within the DR52 haplotype group, the DRB1 and DRB3 transcripts had the same abundance. Taken together, these results are in good agreement with the previously reported transcriptional activities of the DRB promoters except for DRB1*04, thus suggesting a differential post-transcriptional regulation among the DRB1 mRNAs.
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PMID:Quantitative analysis of the expression of the HLA-DRB genes at the transcriptional level by competitive polymerase chain reaction. 854 11

To assess a potential immunoregulatory role of Schwann cells in the peripheral nervous system we examined whether they are able to secrete nitric oxide metabolites. Schwann cells treated with IFN-gamma and TNF-alpha upregulated iNOS-specific mRNA within 12 hr and released nitrite in a time- and dose-dependent manner, reaching a plateau of secretion after 3 days. Nitrite secretion was inhibited by NMMA, suggesting that Schwann cells are endowed with a cytokine-inducible NO synthase. TGF-beta and IL-1 failed to modulate nitrite release. When assessing their role as APC, we note that Schwann cells activated CD4+ antigen-specific T-cell lines, but in contrast to professional thymic APC this ability declined markedly after Day 1. Theoretically diminished T-cell proliferation and finally death might be achieved by secretion of nitric oxide metabolites by Schwann cells. Inhibition of NO production by NMMA did not restore T-cell proliferation after Day 2 or prevent apoptosis of T-cells. However, in a coculture model Schwann cells exerted a strong suppressive effect on T-cell activation by thymic APC, which was almost completely abrogated by addition of NMMA. We suggest that Schwann cells may exert potent immunoregulatory functions beyond their role as APC. They may terminate immunoinflammatory reactions in the peripheral nervous system by releasing NO.
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PMID:Secretion of nitrite by Schwann cells and its effect on T-cell activation in vitro. 859 41