Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06126 (CD1a)
 2,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epidermal Langerhans cells express only very few Class I major histocompatibility complex (MHC) antigens, whose ability to present peptides released from the breakdown of endogenous proteins has not been investigated to date. Langerhans cells strongly express a "nonconventional" Class I molecule, the CD1a antigen. The role played by this antigen on the surface of Langerhans cells remains unelucidated: either release or uptake of peptides derived from the body has been speculated. Langerhans cells also express Class II MHC antigens and in vitro freshly recovered Langerhans cells are capable of capturing antigens, processing them and presenting the resulting peptides associated with Class II MHC molecules to immunocompetent cells. This property is not, however, permanent. Cultured Langerhans cells are no longer capable of processing antigens because they lose their ability to (i) acidify endosomes and (ii) produce the alpha, beta and invariant chains of class II MHC molecules. Cultured Langerhans cells acquire the capacity of stimulating T lymphocytes. This contrast between the in vitro properties of freshly recovered and cultured Langerhans cells may reflect in vivo differences between epidermal Langerhans cells and Langerhans cells which have migrated to regional lymph nodes.
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PMID:[Langerhans cells and presentation of antigens]. 160 51

The structural similarities of CD1a molecules to major histocompatibility complex (MHC) class I antigens, as well as their expression on epidermal antigen-presenting cells suggest that CD1a molecules might be involved in the cutaneous immune response. In the present study, we investigated the effect of different anti-CD1a monoclonal antibodies (BL6, DMC1, and Na1/34) on T cell proliferation induced by allogeneic epidermal cells in vitro. A significant inhibition of the mixed skin cell-lymphocyte reaction was obtained with BL6 and DMC1 monoclonal antibodies (MoAb), which recognize the same epitope on CD1a molecule. The observed inhibition could not be related to a steric hindrance of MHC class II molecules, because Na1/34 MoAb, which reacts with another epitope on CD1a molecule, had no significant effect. BL6 and DMC1 MoAb interfered with an early event of T-cell activation, as shown by a time-course study. In the presence of these MoAb, the addition of exogenous interleukin 2 did not restore T-cell proliferation. Furthermore, the inhibitory effect of anti-CD1a MoAb was not mediated by a suppressor factor released by Langerhans cells (LC). These present data suggest that CD1a molecule may have an important function in self peptide presentation by human Langerhans cells.
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PMID:A potential role for CD1a molecules on human epidermal Langerhans cells in allogeneic T-cell activation. 171 29

The molecules encoded by the major histocompatibility complex play a pivotal role in regulatory interactions between cells of the immune system, which can result in the activation and function of T cells. The function of the CD1 molecules, which are homologous to the major histocompatibility complex-encoded molecules but are encoded on human chromosome 1, is not known. HLA class I molecules and CD1a heavy chains share the ability to associate with several different cell-surface molecules. We show here, by several technical approaches, that HLA class I molecules are associated with CD1a heavy chains on the surface of normal thymus cells. The functional significance of this association during T-cell differentiation is discussed.
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PMID:HLA class I molecules are associated with CD1a heavy chains on normal human thymus cells. 245 69

The CD1 locus encodes a family of major histocompatibility complex (MHC) antigen-like glycoproteins which associate with beta 2-microglobulin and are expressed on immature thymocytes and Langerhans cells. Three CD1 molecules have been identified by monoclonal antibodies and molecular cloning: CD1a, -b, and -c. We have isolated a cDNA coding for a fourth CD1 molecule from a human thymocyte library and termed this molecule CD1d. Reported here are the complete nucleotide sequence and genomic organization of CD1d. They predict that this molecule is related to the previously identified CD1a, -b, and -c molecules and to MHC class I molecules, with three external domains, a transmembrane domain, and a short cytoplasmic tail. The sequence of CD1d is the most divergent among the CD1 molecules in the membrane-distal alpha 1 and alpha 2 domains and in the 5' untranslated region. In contrast, all four CD1 molecules are highly homologous in the membrane-proximal alpha 3 domain, which is likely involved in beta 2-microglobulin binding. A comparison of CD1 and MHC class I sequences suggests that these molecules each evolved to interact with a distinct set of cell surface proteins.
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PMID:Isolation and characterization of a cDNA and gene coding for a fourth CD1 molecule. 246 22

Human cluster-of-differentiation 1 (CD1) is a family of cell surface glycoproteins of unknown function expressed on immature thymocytes, epidermal Langerhans cells and a subset of B lymphocytes. Three homologous proteins, CD1a, b and c, have been defined serologically, and the CD1 gene locus on human chromosome 1 contains five potential CD1 genes. Analysis of the predicted amino-acid sequences of CD1 molecules reveals a low but significant level of homology to major histocompatibility complex (MHC) class I and class II molecules, and, like MHC class I molecules, CD1 molecules are associated non-covalently with beta 2-microglobulin. These structural similarities to known antigen-presenting molecules, together with the expression of CD1 on cells capable of antigen presentation, suggest a role for CD1 molecules in antigen recognition by T cells. Here we demonstrate the specific recognition of CD1a by a CD4-CD8- alpha beta T-cell receptor (TCR) expressing cytolytic T lymphocyte (CTL) line and the specific recognition of CD1c by a CD4-CD8- gamma delta TCR CTL line. The interaction of CD1-specific CTLs with CD1+ target cells appeared to involve the CD3-TCR complex, and did not show evidence of MHC restriction. These results suggest that for a subset of T cells, CD1 molecules serve a function analogous to that of MHC class I and II molecules.
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PMID:Recognition of cluster of differentiation 1 antigens by human CD4-CD8-cytolytic T lymphocytes. 247 5

Human CD1 is a family of thymocyte differentiation antigens which consist of heavy chains with mol. wts between 43 and 49 kd binding to beta 2 microglobulin. They are distant relatives of the major histocompatibility complex (MHC) class I and II products. Five human CD1 genes have been described. Three (CD1A, -B and -C) code for the serologically defined CD1a, -b and -c antigens. The protein products of the other two genes, CD1D and CD1E, remain unknown. All CD1 genes are located on chromosome 1 and hence are independent of the MHC locus. In this paper, the tight linkage of the CD1 genes has been established by pulse field gel electrophoresis, cosmid cloning and walking techniques. The 190 kb of DNA linking all five CD1 genes has been spanned by 14 overlapping cosmids. The order of the genes in the CD1 complex is CD1D-CD1A-CD1C-CD1B-CD1E, and, with the exception of CD1B, they are arranged in the same transcriptional orientation. The genes are evenly spaced in the complex except for the distance between CD1D and CD1A, which is two to three times greater than the average.
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PMID:A physical map linking the five CD1 human thymocyte differentiation antigen genes. 258 17

The expression of immune associated surface antigens of keratinocytes was studied in human papillomavirus (HPV) derived lesions in order to determine whether HPV types have a regulatory role in the pathogenesis of papillomas. A series of cutaneous and mucosal lesions were immunolabeled with monoclonal antibodies to the major histocompatibility complex class 1 (beta 2-microglobulin) and 2 (HLA-DR antigens), intercellular adhesion molecule (ICAM-1) and glycoprotein CD36 (OKM5) as well as CD1a (Langerhans cells), CD4, CD8 (T cells) and CD11a (LFA1 antigen). Testing for the presence of HPV was carried out by in situ hybridization with biotinylated probes for viral DNA detection and typing. We observed a drastic reduction or a loss of beta 2-microglobulin by keratinocytes from cutaneous lesions in correlation with the disappearance of Langerhans cells. Only mild alterations were observed in mucosal lesions. HLA-DR expressed by keratinocytes was only detected in condylomas and laryngeal papillomas and was usually associated with a dense inflammatory reaction. This HLA-DR expression may be correlated with an up-regulation of ICAM-1 and the presence of LFA1 positive leukocytes, mainly of CD8 phenotype, in the epithelium. CD36 was detected on differentiated keratinocytes of all lesions; its expression seems related to the proliferation state of the lesions and probably does not represent an immune marker. The different reactivity patterns observed in cutaneous and mucosal lesions may reflect: 1. different roles for mucosal and cutaneous HPV types in the induction of immunoregulatory surface antigens of keratinocytes, or 2. the changing nature of the cytokines released by mononuclear cells and infected keratinocytes in these lesions.
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PMID:Expression of immune associated surface antigens of keratinocytes in human papillomavirus-derived lesions. 750 44

The CD1 gene family is composed of five distinct molecules: CD1a, b, c, d and e. CD1a, b and c are primarily expressed thymically with limited extrathymic expression. Preliminary studies have shown that CD1d is primarily expressed extrathymically in gastrointestinal epithelial cells, renal tubular epithelial cells and B cells. This report characterizes the expression of CD1d in a variety of human tissues by immunohistochemistry using two anti-human CD1d monoclonal antibodies (mAb). CD1d was found in a wide range of tissues including the intestine, liver, pancreas, skin, kidney, uterus, conjunctiva, epididymis, thymus and tonsil. Within those tissues CD1d was mainly present in epithelial cells, vascular smooth muscle cells and parenchymal cells. Therefore, the tissue distribution of CD1d is distinct from CD1a-c and classical major histocompatibility complex (MHC) proteins implicating a unique role for CD1d in the immune system.
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PMID:Tissue distribution of the non-polymorphic major histocompatibility complex class I-like molecule, CD1d. 750 19

Human CD1 genes are a family of five non-polymorphic genes that, although homologous to both class I and II major histocompatibility complex genes, map to chromosome 1. Only three of the antigens, CD1a, -b, and -c, have been clustered with monoclonal antibodies. They are noncovalently associated with beta 2-microglobulin and may function as nonclassical antigen-presenting molecules. Here we analyze their expression in mouse myeloma transfectants and human thymocytes and find mRNA splicing complexity. This manifests itself as incomplete splicing, alternative splicing, utilization of cryptic splice sites, and the generation of alternative reading frames. In the case of CD1A transfectants, we demonstrate that the major protein product is secreted and show by amino acid sequence analysis that this is derived from an unspliced transcript. A second major CD1a component appears to be retained intracellularly. The production of alternatively spliced transcripts in the thymus is not a feature of all CD1 genes. Although in the case of CD1A only the transcript encoding the cell surface CD1a isoform is found, CD1C and -E produce complex intrathymic splicing patterns. The CD1C transcripts predict the expression of a secreted CD1c isoform in the human thymus, which we detect in CD1C transfectant culture supernatants. CD1 gene expression is thus characterized by considerable splicing complexity, and the difference between the splicing patterns found in different environments suggests that this is tissue specific.
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PMID:Alternative splicing generates secretory isoforms of human CD1. 751 59

Human lymphocyte antigen (HLA) class I proteins of the major histocompatibility complex are largely dependent for expression on small peptides supplied to them by transporter associated with antigen processing (TAP) protein. An inherited human deficiency in the TAP transporter was identified in two siblings suffering from recurrent respiratory bacterial infections. The expression on the cell surface of class I proteins was very low, whereas that of CD1a was normal, and the cytotoxicity of natural killer cells was affected. In addition, CD8+ alpha beta T cells were present in low but significant numbers and were cytotoxic in the most severely affected sibling, who also showed an increase in CD4+CD8+ T cells and gamma delta T cells.
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PMID:Homozygous human TAP peptide transporter mutation in HLA class I deficiency. 751 74


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