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)

Langerhans cells and thymocytes were comparatively studied for their monoclonal antibody-induced endocytic activity. The two cell types were CD1a or Class I-HLA immunolabeled, incubated under similar conditions and the effects induced on membrane mobility were analyzed by a fluorescence method for the thymocytes and at the ultrastructural level for both cell types. We provide evidence that thymocytes are able to cap and internalize by receptor-mediated endocytosis CD1a antigen and Class I-HLA, whereas Langerhans cells present only a process of internalization by receptor-mediated endocytosis for both membrane antigens.
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PMID:Comparative study of in vitro CD1a and HLA-class I antigens endocytosis by human thymocytes and Langerhans cells. 247 27

The T-cell surface differentiation antigens expressed on cortical thymocytes are composed of 3 molecules, CD1a (Mr 49,000), CD1b (Mr 45,000), and CD1c (Mr 43,000), which are non-covalently attached to beta 2-microglobulin. In the present study, differences in quantitative binding (immunogold labelling) were observed with four CD1a monoclonal antibodies (mAb), Na1/34, L544, Vit6 and OKT6, on epidermal Langerhans cells obtained through trypsinization and Ficoll-Hypaque sedimentation. These cells were surface-labelled with 125I and then lysed. Immunoprecipitation was carried out with five CD1a mAb, BL6, 10D12.2, L404, L544 and OKT6, and immunoprecipitates were electrophoretically run. All CD1a mAb except OKT6 immunoprecipitated an additional molecule with an apparent relative mass of 27,000, under reducing conditions. CD1a antigen (Mr 49,000) was borne by the same chain of Mr 49,000 on cortical thymocytes and Langerhans cells, whereas the Mr 27,000 molecule was never found on thymic cells. On two-dimensional gel analysis, the Mr 27,000 molecule showed a pattern with 3 major spots with pI of 5.6, 5.9 and 6.2. This Mr 27,000 protein was found to contain one N-linked oligosaccharide residue by endoglycosidase-F treatment. By sequential immunoprecipitation, this Mr 27,000 molecule was shown to be different from the major histocompatibility complex class II beta-chains (DR, DP). As the Mr 27,000 molecule was not precipitated with OKT6, sequential immunoprecipitation confirmed specific recognition of this low molecular weight protein by other CD1a mAb. The protein of apparent molecular mass 27,000 was considered to be a breakdown product of Mr 49,000 (CD1a) antigen. These results suggested that the CD1a molecule was sensitive to trypsin.
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PMID:Cleavage of Langerhans cell surface CD1a molecule by trypsin. 247 41

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

Apparently normal, and lesional skin from patients with atopic eczema were investigated immunohistochemically with anti-HLA-DR, -CD1a and -IgE antisera. A CD1a+ intercellular pattern was observed in uninvolved skin in the majority of the patients whereas an HLA-DR+/CD1a+ network, mostly localized in basal and supra-basal areas, was shown in lesional skin of virtually all of them. Moreover, an HLA-DR+/CD1a+IgE+ intercellular pattern was observed in some of the patients only and was predominantly localized in those areas characterized by lymphocyte exocytosis, spongiosis or vesicle formation. Whether keratinocytes are able to synthesize CD1a antigen and Fc epsilon R or if these molecules are only produced and shed by CD1a+/IgE+ epidermal dendritic cells remains unclear.
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PMID:Keratinocytes in lesional skin of atopic eczema bear HLA-DR, CD1a and IgE molecules. 247 18

The CD45R and CDw29 antigens are expressed on naive and primed helper T cell populations which serve suppressor-inducer or helper-inducer functions, respectively. These antigens may also be expressed on epithelial cell subpopulations. In the present study, monoclonal antibodies reacting with T lymphocytes and Langerhans cells (LC) were used to characterize the expression of CD45R and CDw29 antigens in oral lichen planus. CDw29 was expressed by LC and lymphocytic cells whereas keratinocyte reactivity varied from negative through to full thickness staining. Expression of CD45R was confined to intraepithelial cells with either lymphocytic or dendritic morphology. A relatively constant ratio of CD1a + LC to CD45R + cells (2:1) was seen. These results demonstrate the existence of intraepithelial cells expressing antigens which are functionally important in T cell responses and which may provide local immunoregulatory influences.
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PMID:Expression of CDw29 and CD45R antigens on epithelial cells in oral lichen planus. 247 98

Human cord blood (CB) mononuclear cells were fractionated into peanut agglutinin positive (PNA+) and PNA negative (PNA-) subsets. The PNA+ subset was enriched for T6+(CD1a)Ia+ cells, which we have previously shown to resemble the Langerhans cells (LCs) of the skin, and therefore described as circulating LCs precursors. Supernatants of PNA+ and PNA- cells, and of FACS purified populations of T6+ CB cells, cultured with and without LPS, were tested for IL-1 activity. It was found that cord blood PNA+ mononuclear cells as well as purified populations of T6+ CB cells produce significant amounts of, both extracellular and cell associated, IL-1 as compared to PNA- and T6- cells, and comparable to those produced by macrophages. LPS stimulation mainly affected T6+ cells. It can be concluded that cord blood T6+ cells, presumably LCs precursors, are capable of IL-1 production.
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PMID:IL-1 production by T6 (CD1a) positive cord blood mononuclear cells (Langerhan's cell precursors?). 247 42

Bone marrow cells of a patient with Letterer-Siwe disease were cultured for three weeks in long-term bone marrow culture (LTBMC) conditions and examined at one-week intervals with a large panel of monoclonal antibodies by immunohistochemistry and by the immunogold transmission electron microscopy (immunoTEM) technique. Although at diagnosis the bone marrow showed a slight increase of monocytes with a normal phenotype, a rapid expansion of cells expressing CD1a and CD1c was observed already after 1 week of culture. A progressive increase in CD4, CD11b and CD11c expression was also observed. ImmunoTEM of cultured cells demonstrated that CD1a+ cells had macrophage-like morphology, and did not contain Birbeck granules. These findings indicate that bone marrow monocytes acquire some phenotypical features of Langerhans cells in LTBMC and support the hypothesis that these cells may derive directly from a bone marrow monocytic precursor.
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PMID:Bone marrow monocytes in histiocytosis X acquire some phenotypic features of Langerhans cells in long term bone marrow cultures. 247 66

Fc gamma-receptors (FcR) in cryostat sections of normal human skin were detected with soluble immune complexes of horseradish peroxidase (HRP) and rabbit IgG anti-HRP (HRP-anti-HRP). The binding of HRP-anti-HRP to Langerhans' cells (LC) was demonstrated using a double immunofluorescence staining in which LC were identified with a CD1a specific monoclonal antibody (Leu 6). The immune complexes gave granular staining of CD1a+ epidermal cells in sections of all specimens from normal skin. The mean percentage of CD1a+ cells that were FcR+ was 49 +/- 11 (n = 8). The FcR+/CD1a+ cells had a clearly defined dendritic pattern. The staining intensity of LC with HRP-anti-HRP was weaker than the intense staining of CD1a-macrophages in the dermis. Results of inhibition experiments indicate that human epidermal LC express low affinity FcR, but the presence of high affinity FcR as well cannot be excluded. The demonstration of FcR expression on normal LC clarifies previous uncertainty on LC membrane receptors, though the functional significance of these receptors is still not well understood.
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PMID:Fc gamma-receptor as a functional marker on epidermal Langerhans' cells in situ. 248 27

The distribution of CD1a antigen in gingival epithelium of clinically healthy gingiva was examined and compared with the distribution in gingival epithelium of adult periodontitis lesions. Cryostat sections were examined with monoclonal antibodies to CD1a antigen using the ABC immunoperoxidase technique. In healthy gingiva, CD1a was limited to Langerhans cells (LC) which were observed throughout the length of the external epithelium and orosulcular epithelium. The numbers of LC expressed either per unit length of orosulcular epithelium or per mm2 were similar to the numbers in external gingiva. Junctional epithelium contained few if any dendritic LC. The numbers of LC in pocket epithelium of adult periodontitis lesions were significantly lower compared with orosulcular epithelium of healthy tissue and compared with external gingiva of diseased tissue (p less than 0.005). In many sections, no LC were identified in pocket epithelium. In 5 of 8 adult periodontitis sites, CD1a was also observed in association with the membranes of suprabasal keratinocytes in external and pocket epithelium in areas where no LC were identified. These findings provide further evidence that changes in gingival epithelial cells occur in periodontal disease which are analogous to those documented in dermatological diseases and suggest that epithelium may play a role in gingival homeostasis and in the pathogenesis of periodontal diseases.
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PMID:The distribution of Langerhans cells and CD1a antigen in healthy and diseased human gingiva. 248 34

The differentiation of two types of T-lymphocyte accessory cells, i.e., interdigitating reticulum cells and Langerhans cells, was studied immunocytochemically and ultrastructurally on cutaneous lesions from patients with mycosis fungoides, a neoplasm of mature T-lymphocytes. In such a condition the lymphoid infiltrate creates, adjacent to the epidermis, a microenvironment in the dermis similar to that of T-cell areas of lymphoid organs. Immunocytochemistry revealed that CD11c+ CD1a- putative monocytic cells co-exist with CD11c+ CD1a+ putative mature accessory cells. By electron microscopy, large numbers of interdigitating reticulum cells in the dermal infiltrate and Langerhans cells in the epidermis were found. Furthermore, monocytes were frequently observed, at times with cells showing intermediate features between monocytes and interdigitating reticulum cells on the one hand and Langerhans cells on the other. In the absence of proliferative phenomena of the above cells, it is conceivable that both interdigitating reticulum cells and Langerhans cells originate from locally migrated monocytes. A possible role of the local tissue micro-environment--namely the T-lymphoid microenvironment for interdigitating reticulum cells and the epidermal microenvironment for Langerhans cells--in inducing the differentiation of monocytes into the two kinds of accessory cells is proposed.
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PMID:Differentiation of interdigitating reticulum cells and Langerhans cells in the human skin with T-lymphoid infiltrate. An immunocytochemical and ultrastructural study. 251 48


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