Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We applied an enzyme-linked immunospot (ELISPOT) assay for the detection and quantification of blood-derived CD8+ T cells recognizing peptide antigens presented by HLA-A2.1. CD8+ T lymphocytes were isolated from peripheral blood and were stimulated for 40 h with peptide-loaded A2.1-positive 0.174 x CEM.T2 cells. Tumor necrosis factor alpha (TNF-alpha) secreted by single T cells in response to antigen contact was trapped on nitrocellulose membranes precoated with anti-TNF-alpha antibodies and was then immunochemically visualized as spots. With this assay, up to 25% of cloned cytolytic T lymphocytes (CTL) were detected during the test period that recognized defined melanoma antigens in association with HLA-A2.1. CD8+ lymphocytes responsive to a known immunogenic HLA-A2.1-binding peptide from reverse transcriptase of the human immunodeficiency virus (HIV) were only detectable in HIV-infected patients, but not in anti-HIV-negative donors. T cells reacting with a peptide derived from a mutated cyclin-dependent kinase 4 (CDK4-R24C) were exclusively detected among CD8+ lymphocytes isolated from blood of the patient, whose melanoma had previously been found to carry the CDK4-R24C allele. T cells responding to HLA-A2.1-associated peptides of normal melanocyte differentiation antigens tyrosinase and Melan-A/MART-1 were found at low frequencies in almost all donors tested, which might reflect a natural autoimmunity to these antigens. However, in a melanoma patient we found a few days after surgery of melanoma metastases high frequencies of T cells against Melan-A/MART-1 and tyrosinase peptides (up to 38 per 10(5) CD8+ T cells), which gradually decreased during the following months. In an HIV-infected patient with progressive disease we observed a loss of T cells reactive with the HIV reverse transcriptase peptide. These observations provide evidence that peptide-dependent TNF-alpha spot formation in vitro resulted from previous antigen exposure in vivo. Therefore, the TNF-alpha ELISPOT assay might be useful in monitoring antigen-specific T lymphocyte responses during the natural course of diseases as well as during therapeutic interventions aiming at the induction of protective T cell immunity. In addition, it might help to identify immunodominant T cell epitopes.
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PMID:Detection and quantification of blood-derived CD8+ T lymphocytes secreting tumor necrosis factor alpha in response to HLA-A2.1-binding melanoma and viral peptide antigens. 866 32

A key function of the Nef protein of immunodeficiency viruses is the downregulation of the T-cell and macrophage coreceptor, CD4, from the surfaces of infected cells. CD4 downregulation depends on a conserved (D/E)XXXL(L/I)-type dileucine motif in the C-terminal, flexible loop of Nef, which mediates binding to the clathrin adaptor complexes AP-1, AP-2, and AP-3. We now report the identification of a consensus (D/E)D motif within this loop as a second, conserved determinant of interaction of Nef with AP-2, though not with AP-1 and AP-3. Mutations in this diacidic motif abrogate both AP-2 binding and CD4 downregulation. We also show that a dileucine motif from tyrosinase, both in its native context and in the context of Nef, can bind to AP-2 independently of a diacidic motif. These results thus identify a novel type of AP-2 interaction determinant, support the notion that AP-2 is the key clathrin adaptor for the downregulation of CD4 by Nef, and reveal a previously unrecognized diversity among dileucine sorting signals.
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PMID:A diacidic motif in human immunodeficiency virus type 1 Nef is a novel determinant of binding to AP-2. 1803 17