Biomedical subjects

W M Gallatin

Publications and source records attributed to W M Gallatin.

At least 37 records · Page 2Linked to original sources

PubMed1995

A novel leukointegrin, alpha d beta 2, binds preferentially to ICAM-3.

The leukocyte-restricted beta 2 (CD18) integrins mediate cell adhesion in a variety of events essential for normal immune function. Despite extensive research in this field, only three members of this integrin subfamily have been described: CD11a/CD18 (LFA-1), CD11b/CD18 (Mac-1), and CD11c/CD18 (p150,95). We have identified a cDNA encoding a fourth alpha chain, alpha d, that associates with CD18. The alpha d subunit is more closely related to CD11b and CD11c than to CD11a. This integrin is expressed at moderate levels on myelomonocytic cell lines and subsets of peripheral blood leukocytes, and more strongly on tissue-compartmentalized cells such as foam cells, specialized macrophages found in aortic fatty streaks that may develop into atherosclerotic lesions. The alpha d/CD18 molecule exhibits preferential recognition of ICAM-3 over ICAM-1.

Amino Acid Sequence↗

PubMed1995

The ICAM-3/LFA-1 interaction is critical for epidermal Langerhans cell alloantigen presentation to CD4+ T cells.

Intercellular adhesion molecule (ICAM)-3 is a recently described member of the immunoglobulin superfamily and, as such, is closely related to ICAM-1 and ICAM-2. All three ICAMS are cognate for the counter-receptor lymphocyte function associated antigen-1 (LFA-1, CD11a/CD18). Unlike ICAM-1 and ICAM-2, ICAM-3 is constitutively expressed at high levels on resting leucocytes. We investigated the expression and function of ICAM-3 in normal skin (n = 5), as well as its expression in psoriasis (n = 4), atopic eczema (n = 4), allergic (rhus) contact dermatitis (n = 3), and cutaneous T-cell lymphoma (CTCL, n = 2). Five-micrometre cryostat sections of skin were stained using monoclonal antibodies to ICAM-3 and a well characterized immunoperoxidase technique. In normal skin, ICAM-3 was expressed by all cutaneous leucocytes but most striking was the strong expression of ICAM-3 by Langerhans cells within both epidermis and dermis. This observation was confirmed by double-labelling with CD1a and negative staining with an IgG1 isotype control. In psoriasis, atopic eczema, allergic contact dermatitis, and CTCL, ICAM-3 was co-expressed on all CD1a+ cells, although, in psoriasis, the intensity of ICAM-3 expression was reduced. Functional blocking experiments were performed to determine whether the observed ICAM-3 expression on Langerhans cells was functionally important in antigen presentation. CD4+ T cells were prepared from peripheral blood and 10(5) CD4+ T cells combined with 10(5) epidermal cells harvested from keratome biopsies of normal skin of an individual allogeneic to the T-cell donor. Addition of 50 micrograms anti-ICAM-3 to the co-culture resulted in a consistent (50%) reduction in degree of alloantigen presentation by Langerhans cells to T cells. Inhibition was 77% of that produced by the addition of anti-LFA-1. These data indicate that ICAM-3 is constitutively expressed by Langerhans cells and is a major ligand for LFA-1 on CD4+ T cells during their response to Langerhans cells. Because fresh Langerhans cells constitutively express little ICAM-1, whereas ICAM-3 is constitutively expressed at high levels, it would appear that ICAM-3 is the dominant functional ICAM on in situ Langerhans cells in the normal epidermis.

Antigen Presentation↗

PubMed1994

LFA-1 binding site in ICAM-3 contains a conserved motif and non-contiguous amino acids.

The intercellular adhesion molecule-3 (ICAM-3) is a counter receptor for the integrin LFA-1 that supports cell-cell adhesion dependent functions. ICAM-3 is a member of the immunoglobulin superfamily possessing five immunoglobulin-like domains. Here, we characterize the overall shape of ICAM-3 and the amino acid residues involved in binding LFA-1 and monoclonal antibodies (Mab). Electron microscopic observations show that ICAM-3 is predominantly a straight rod of 15 nm in length, suggesting a head to tail arrangement of the immunoglobulin-like domains. Six out of nine ICAM-3 Mab described blocked the interaction with LFA-1 to varying degrees. Domain assignment of blocking Mab epitopes and characterization of LFA-1-dependent cell adhesion to ICAM-3 mutants demonstrate that the amino-terminal domain of ICAM-3 interacts with LFA-1. A conserved amino acid motif including residues E37 and T38 form an integrin binding site (IBS) in ICAM-3. This motif has also been shown to function as an IBS in ICAM-3 and VCAM-1 and hence many form a common site of contact in all CAMs of this type. Other ICAM-3 residues critical to adhesive interactions, such as Q75, conserved in ICAM-1 and ICAM-2, but not VCAM-1, may confer specificity to LFA-1 binding. This residue, Q75, is predicted to locate in a model of ICAM-3 to the same site as RGD in the immunoglobulin-like domain of fibronectin that binds several integrins. This suggest an evolutionary relationship between ICAMs and fibronectin interactions with integrins.

Amino Acid Sequence↗

PubMed1993

Syn-capping of human T lymphocyte adhesion/activation molecules and their redistribution during interaction with endothelial cells.

Lymphocyte-endothelial cell interactions are mediated in part by multiple lymphocyte surface adhesion/activation molecules and their cognate ligands. We investigated the surface localization of several of these molecules implicated in T cell adhesion and transendothelial migration mechanisms to determine if spatial regulation of their distribution contributes to these processes. T lymphocyte suspensions were stained to define distribution, ability to be aggregated into energy-dependent caps, and potential cocapping of several adhesion structures. CD2, CD44, L-selectin (LAM-1, LECCAM-1), and CD11a/CD18 (LFA-1) exhibited uniform distribution on the T cell surface by direct immunofluorescence but formed caps in an energy-dependent, and therefore cytoskeletally driven, manner when examined by indirect immunofluorescence. CD2 was shown to syn-cap (unidirectionally cocap) with CD44 and CD11a/CD18 (LFA-1), an observation potentially related to functional cooperation among these molecules in T cell activation. T cells were also added to endothelial cell monolayers to assess, in a physiologically relevant context, potential surface molecule reorganization. Lymphocytes co-cultured with human umbilical vein endothelial cells (HUVEC) underwent a profound shape change, from essentially round cells to polarized cells bearing pseudopodia. Immunofluorescent localization of T cell adhesion/activation molecules using confocal microscopy revealed the redistribution of CD2, CD44, and L-selectin to the pseudopod. In contrast, CD11a/CD18 remained globally distributed on the cell surface, even in severely deformed cells. Both lymphocyte shape change and membrane molecule redistribution appear to be cell-cell contact-dependent phenomena requiring intact, viable endothelial cells. Mechanisms that control these events may be critical to lymphocyte recirculation and inflammation.

Antibodies, Monoclonal↗

PubMed1993

Human immunodeficiency virus infection among high-risk seronegative prostitutes in Nairobi.

To determine the frequency and duration of antibody-negative human immunodeficiency virus (HIV) infection among heterosexually exposed African women, 56 HIV-seronegative female prostitutes in Nairobi were studied. Polymerase chain reaction (PCR) was used to detect HIV DNA in peripheral blood at enrollment, and women were followed prospectively with serologic testing to determine HIV seroincidence. Six women (11%) were infected with HIV by PCR criteria at enrollment. Seroconversion occurred in 5 of these subjects within 1-12 months, while the sixth remained seronegative when last evaluated at 5 months. The cumulative annual seroconversion rate in the entire cohort was 38%. Using maximum likelihood analysis, the mean interval between HIV infection and seroconversion was estimated to be between 3 and 4 months, similar to that described for homosexual men and blood product recipients in the United States. Prolonged HIV infection in the absence of antibodies appears to be uncommon in this setting.

Adult↗

PubMed1992

Cloning and characterization of a new intercellular adhesion molecule ICAM-R.

The human intercellular adhesion molecules ICAM-1, ICAM-2 and their counter-receptors, the beta 2 or leukointegrins, mediate a variety of homotypic and heterotypic leukocyte and endothelial cell-cell adhesions central to immunocompetence. It has been found that cell-cell adhesion which is dependent on expression of the leukocyte function-associated antigen LFA-1 is not always blocked completely by antibodies raised against ICAM-1 and ICAM-2. Other leukointegrin ligands therefore probably exist, such as a glycoprotein of M(r) 124K that binds LFA-1 and has been designated ICAM-3 on the basis of this function. We have molecularly cloned a new member of the ICAM family, ICAM-R, which is related to ICAM-1 and ICAM-2. The complementary DNA encoding ICAM-R is 1,781 base pairs long and the protein has five extracellular immunoglobulin-family type domains. The mature cell-surface form of the ICAM-R protein has an M(r) which varies from 116 to 140K in a cell type-specific fashion. Overall identities in protein sequence with ICAM-1 and ICAM-2 are 48% and 31% respectively, with the degree of similarity varying between individual domains. The high level of expression of ICAM-R on resting leukocytes of all lineages and its lack of expression on either resting or cytokine-activated endothelial cells indicates a pattern of expression distinct from ICAM-1 and ICAM-2. In common with ICAM-1 and ICAM-2, ICAM-R is a ligand for the beta 2-integrin CD11a/LFA-1 (CD18).

Amino Acid Sequence↗

PubMed1992

Vascular cell adhesion molecule-1 expressed by bone marrow stromal cells mediates the binding of hematopoietic progenitor cells.

Human bone marrow-derived CD34+ cells were analyzed for the expression of the beta 1-family of integrin adhesion molecules. Integrin alpha 4 beta 1 was consistently expressed by greater than 90% of CD34+ cells, including essentially all assayable granulocyte-macrophage colony-forming cells (CFU-GM) and erythroid bursts (BFU-E) as shown by fluorescence-activated cell sorting studies. Adhesion of highly enriched CD34+ cells to cultured allogeneic marrow stromal cells was largely inhibited both by monoclonal antibody to alpha 4 beta 1 and to vascular cell adhesion molecule-1 (VCAM-1), a ligand for alpha 4 beta 1. VCAM-1 was found to be expressed by bone marrow stromal elements in vitro both constitutively at low level and at high levels after treatment with cytokines. Induction of VCAM-1 was cytokine- and time-dependent with maximum levels being obtained after 4 hours of exposure to a combination of interleukin-4 and tumor necrosis factor-alpha. Cytokine-induced stromal cells bound threefold higher numbers of CFU-GM and BFU-E, this increase being abrogated by anti-alpha 4 beta 1 and anti-VCAM-1 antibodies. In addition, the adhesion to stroma of more immature progenitors, the long-term culture initiating cells, also occurred through an alpha 4 beta 1/VCAM-1-dependent mechanism. These studies identify an adhesion mechanism of potential importance in the localization of primitive progenitors within the hematopoietic microenvironment.

Antibodies, Monoclonal↗

PubMed1991

FMC46, a cell protrusion-associated leukocyte adhesion molecule-1 epitope on human lymphocytes and thymocytes.

In this report, we describe a 76-kDa glycoprotein recognized by mAb FMC46 that, by virtue of its concentration on cell protrusions involved in motility, may be important in lymphoid cell locomotion. FMC46 detects an epitope of the leukocyte adhesion molecule-1 (LAM-1), a member of the selecting family (LAM-1, Endothelial Leukocyte Adhesion Molecular-1 (ELAM-1), and Granule Membrane Protein-140 (GMP-140), that is expressed on LAM-1-transfected cell lines, is a glycosylation epitope based on its loss after culture in tunicamycin, and is closely related to the LAM-1.2 epitope. FMC46 is expressed at high density on the majority of CD45RA+ and CD45RO+ peripheral blood T cells (60 to 70%) and on a subset of thymocytes that includes the multinegative CD3- CD4- CD8- progenitor cells (100% FMC46hi) and the CD45R0- presumptive thymic generative lineage (70% FMC46hi). It appears at reduced density and frequency on CD45RA- thymocytes (50% FMC46lo), comprised mainly of death-committed thymocytes. Among thymic subsets defined by expression of CD4 and/or CD8, FMC46 is expressed at high density predominantly on a subset of single-positive cells and not on double-positive cells. These results suggest a fundamental role for LAM-1 in thymic development, with a high density preferentially expressed on cells involved in thymic generative processes and a low density on cells progressing to intrathymic death. A major subset of peripheral blood B cells and thymic B cells also express FMC46. Immunohistochemistry on frozen sections indicated strong staining in splenic follicles and around blood vessels, staining of the thymic medulla and subcapsular areas, and staining of the mantle zone of germinal centers of the lymph node. FMC46+ lymphocytes accumulated along high endothelial venules in the lymph node. On locomoting multinegative thymocytes, FMC46 is concentrated on the leading tip of extended processes, on pseudopods, and on ruffles, unlike the distribution of either CD44 or TQ1 (LAM 1.2), suggesting a role in locomotion. On dividing multinegative thymocytes, FMC46 was found almost exclusively along the cleavage furrow, implicating it in detachment processes. We conclude that the properties of the LAM-1 molecule recognized by FMC46 are consistent with a role in detachment phases of motility and of cell interactions.

Antibodies, Monoclonal↗

PubMed1991

Sequence of the bovine CD44 cDNA: comparison with human and mouse sequences.

CD44 is a cell-surface glycoprotein involved in leukocyte adherence, T-cell activation and lymphocyte homing. We have isolated and sequenced a cDNA clone which encodes for bovine CD44. The predicted amino acid sequence of bovine CD44 has an overall high similarity with that of human and mouse CD44, 79.5 and 73.2%, respectively. In all three species, CD44 has a similar transmembrane region and cytoplasmic tail. In addition, all of the cysteine residues and a majority of the putative N-linked glycosylation sites in the extracytoplasmic domain are conserved between bovine, human and mouse. All three species have an area of low interspecies similarity within the extracytoplasmic domain. This area has a similarity of 34% between bovine and human, 27% between bovine and mouse, and 35% between human and mouse. The location of this area of low similarity is conserved between species.

Amino Acid Sequence↗

PubMed1991

Cell surface glycoconjugates in intercellular and cell-substratum interactions.

Progress in understanding the role of the carbohydrate moieties of cell surface adhesion molecules is evaluated. Functional roles of the oligosaccharides of extracellular matrix glycoproteins are also considered. Selected examples of glycoconjugate participation in cell-cell and cell-substratum interactions are presented with emphasis on systems in which structures of functionally important glycosyl moieties of glycoproteins and glycolipids have been determined. Where available, cases of altered cell adhesive behavior attributable to transformation-associated alterations in glycosylation of adhesion molecules are cited.

Animals↗

PubMed1990

Lymphocyte HEV adhesion variants differ in the expression of multiple gene sequences.

Lymphocyte adhesion to high endothelial venule cells in lymphoid organs of mice is mediated by several cell-surface glycoproteins, one of which, gp90MEL-14, is detected by the MEL-14 monoclonal antibody (mAb). The MEL-14 mAb was used to select two variants of the EL4 cell line, EL4MEL-14-hi and EL4-MEL-14-lo, that have disparate cell surface expression of this adhesion receptor. A cDNA library constructed from EL4MEL-14-hi mRNA was enriched for sequences present at higher levels in EL4MEL-14-hi cells than EL4MEL-14-lo cells. Quantitative analysis of candidate differential clones by RNA probe protection methods identified five clones whose steady-state mRNA levels were increased in the EL4MEL-14-hi cells. One of these clones, DIFF6, is derived from an RNA whose expression level is higher in several cell lines producing high amounts of MEL-14-reactive gp90, and absent or present at lower levels in several cell lines expressing low levels of this glycoprotein. However, DIFF6 does not encode gp90MEL-14. The nucleotide sequence of this clone predicts a relatively hydrophilic protein characteristic of a cytoplasmic or nuclear protein. Present experiments indicate that expression of gp90MEL-14, a cell-surface-adhesion receptor molecule, may be coregulated with additional cytoplasmic or nuclear factors.

Amino Acid Sequence↗

PubMed1990

IL-4 acts synergistically with IL-1 beta to promote lymphocyte adhesion to microvascular endothelium by induction of vascular cell adhesion molecule-1.

Adhesion of lymphocytes to endothelial cells (EC) is the requisite first element in the multistep process of transmigration from blood across the postcapillary venules. Selective expression of cell adhesion molecules (CM) by microvascular EC in lymphoid organs (e.g., lymph nodes) and during tissue inflammation modulates this traffic in a site-directed manner. CAM synthesis by EC is regulated in turn by cytokines released in the local microenvironment. Studies done largely with human umbilical vein EC have implicated IL-1, IFN-gamma, and TNF-alpha as cytokines which promote leukocyte adhesion to EC. In the work reported here, the responses of cultured microvascular EC derived from macaque lymph nodes to IL-1beta, IL-2, IFN-gamma, and IL-4 were examined. Increases in lymphocyte adhesion after preculture of microvascular EC in IL-1beta or IFN-gamma were typically 2-to 4-fold above controls and comparable to those reported for human umbilical vein EC. IL-2 had no effect. In contrast, IL-4 markedly enhanced adhesion to microvascular EC. IL-4-induced adhesion was observed as early as 4 h after induction, plateaued by 24 h, was stable through 72 h of culture, but decayed to basal levels within 72 h after removal of IL-4 from the cultures. IL-1beta, but not IL-2 or IFN-gamma, synergistically enhanced the action of IL-4 on cultured microvascular EC to promote lymphocyte binding. Adhesion triggered in this manner required de novo protein synthesis. However, the avidity of IL-4-activated microvascular EC for lymphocytes, and analyses of kinetics, cation and temperature dependence, and/or lack of blockade with mAb to endothelial leukocyte adhesion molecule-1, intra-cellular adhesion molecule-1, and MECA-79 indicated that these CAM were not central to the phenomenon. To aid identification of the relevant CAM, mAb specific to IL-4-induced microvascular EC were produced. One of these, 6G10, blocked up to 90% of lymphocyte adhesion to IL-4-induced microvascular EC, immunoprecipitated an IL-4-induced cell-surface molecule of 110-kDa molecular mass, and reacted specifically with Chinese hamster ovary cells transfected with human vascular cell adhesion molecule-1. Our results suggest that IL-4 may have potent effects on lymphocyte recirculation in vivo.

Animals↗

PubMed1990

An antibody that facilitates hematopoietic engraftment recognizes CD44.

Pretreatment of recipients with the monoclonal antibody (MoAb) S5 facilitates engraftment of bone marrow from mismatched, unrelated donors in the canine transplantation model. In the direct comparisons reported here, the S5 glycoprotein (gp) was found to have structural homology to CD44 that in humans has been implicated in adhesive interactions of one type of effector cell, the lymphocyte. The S5 antigen and gp90Hermes-1 exhibited codistribution on canine peripheral blood cells. Both S5 and Hermes-1 (anti-CD44) MoAbs recognized 90-Kd species in radioimmune precipitations of 125I surface-labeled canine peripheral blood lymphocytes and bone marrow cells. Competitive antibody binding experiments showed that the epitope detected by S5 was distinct from that bound by Hermes-1 but overlapped with those defined by two other known anti-CD44 reagents, IM7 and Hutch-1. Sequential immunoprecipitation with S5 and Hermes-1 indicated that the two antibodies recognize the same or overlapping subsets of membrane gps. Tryptic digestion of S5 and anti-CD44 immunoprecipitates generated two major iodinated peptides of 27 and 35 Kd in both cases, a further indication of structural homology. Similarly, after N-glycanase digestion, S5 and CD44 immunoprecipitates were resolved to a single 68-Kd species. These findings suggest that CD44-mediated adhesive events may affect the fate of transplanted hematopoietic cells. The previous implications of this gp in T-lymphocyte activation and lymphocyte adhesion to endothelium thus provide useful paradigms to analyze its function in the bone marrow transplant setting.

Amino Acids↗

PubMed1990

Simian immunodeficiency virus is restricted to a subset of blood CD4+ lymphocytes that includes memory cells.

HIV and the related simian immunodeficiency virus (SIV), which causes AIDS in macaques, infect only a small percentage of CD4+ lymphocytes at any point during the disease. We have identified three distinct cellular phenotypes within the CD4+ subpopulation in macaques, based on cell surface expression of CD44 and CD45R, which putatively represent successive stages of postthymic proliferation and functional maturation. Two of these subsets, CD44hi CD45R+, which contained virtually all circulating cells in cycle, and CD44hi CD45R-, which was noncycling and has been linked to immunologic memory, were selectively depleted in SIV-infected animals at an asymptomatic stage of disease. To test whether SIV infection was restricted to cells with this phenotype in vivo, we used the polymerase chain reaction to sensitively detect SIV DNA in purified subpopulations of CD4+ lymphocytes. We found that SIV exclusively infected blood lymphocytes expressing high levels of CD44. Within this subset infection occurred not only in the fraction containing actively proliferating cells (CD45R+), but also in resting, putative memory cells (CD45R-). These data directly demonstrate that cellular maturation stages of normal postthymic T lymphocyte differentiation are important factors in permitting lentivirus infection in vivo, and that noncycling, memory T cells may be a reservoir for SIV.

Animals↗

PubMed1990

Expression of CD44 confers a new adhesive phenotype on transfected cells.

The function of the CD44 glycoprotein as an adhesion molecule was directly tested by transformation of a CD44 cDNA into mouse fibroblasts. This cDNA was expressed as a heavily modified cell surface protein reactive with monoclonal antibodies that recognize glycoproteins now identified in primates as CD44. Independent transfectants exhibited a new self-adhesive phenotype, forming large aggregates when placed in suspension. In variants derived from a clone of cells, aggregation competence segregated with expression of the transfected gene. This CD44-mediated adhesion was blocked specifically by monoclonal antibodies binding one immunologically defined region of CD44. Nontransfected L cells did not self-aggregate but were capable of adhering to the transfectants, indicating that at least one ligand for this adhesion molecule is expressed by mouse fibroblasts.

Animals↗

PubMed1989

Expression of lymphocyte adhesion receptors for high endothelium in primates. Anatomic partitioning and linkage to activation.

Glycoproteins of 90 to 95 kD Mr are involved in adhesion to high endothelium and migration into secondary lymphoid tissues in several species. Recent evidence indicates that in primates, one type of these molecules may be subsumed under the CD44 grouping of lymphocyte differentiation Ag. Flow cytometric analysis of circulating macaque lymphocytes for expression of these structures revealed a prominent bimodal distribution, defining two subpopulations with a 5- to 10-fold difference in immunofluorescence staining intensity. Studies of lymphocytes from different anatomic compartments revealed marked differences in the relative numbers of these two phenotypes: splenic and peripheral blood lymphocytes were mostly CD44hi, whereas thoracic duct lymphocytes, which have recently exited lymph nodes and Peyer's patches, were predominantly CD44lo, suggesting that these subsets may have different migratory behavior in vivo. Activated lymphocytes, as defined by light scatter measurements, expression of IL-2-R, and CD45R levels, were all CD44hi. Simultaneous three parameter flow cytometric determination of CD44 and CD45R expression, and cell-cycle analysis with 7-amino actinomycin D further demonstrated that intrinsically cycling cells were contained in the CD44hi, CD45R+ subset. After stimulation of CD44lo lymphocytes in vitro with cross-linked anti-CD3 antibodies and PMA, CD44 expression markedly increased. These data indicate that CD44 up-regulation is an early event in T lymphocyte activation in vivo, and support the hypothesis that patterns of lymphocyte traffic are regulated in concert with cell activation, possibly by differential expression of CD44.

Animals↗

PubMed1989

Structural homology between lymphocyte receptors for high endothelium and class III extracellular matrix receptor.

We have identified extensive structural homology between one type of heterotypic adhesion receptor (HAR) involved in lymphocyte interactions with high endothelium in lymphoid organs and a collagen-binding protein, termed class III extracellular matrix receptor (ECMRIII), expressed on most nucleated cell types. Both receptors have been described as heterogeneous 90-kDa transmembrane glycoproteins, referred to here as gp90. Monoclonal anti-HAR antibodies, Hermes-1 and Hutch-1, and monoclonal anti-ECMRIII antibodies, P1G12 and P3H9, were utilized to compare the two receptors. (i) All these monoclonal antibodies immunoprecipitated major gp90 components as well as uncharacterized additional higher molecular mass antigens of 120-200 kDa in human and macaque fibroblasts and peripheral blood mononuclear cells. (ii) Competitive binding analyses with the antibodies identified distinct epitopes present on gp90. (iii) Enzymatic and chemical digestions generated identical peptide fragments from all the antigens in human and macaque fibroblasts and peripheral blood mononuclear cells. (iv) Sequential immunoprecipitation with P1G12 followed by the other monoclonal antibodies indicated that all gp90 species reactive with Hermes-1 and Hutch-1 also expressed the P1G12 defined epitope. In reciprocal experiments, Hermes-1 and Hutch-1 immunoprecipitation did not completely remove all P1G12-reactive gp90 from cellular extracts. One inference from these data would be that gp90 is serologically heterogeneous, encompassing HARs as a major subset of this broadly expressed class of molecules.

Animals↗

PubMed1989

Isolation and DNA sequence of a cDNA clone encoding a lymphocyte adhesion receptor for high endothelium.

The migration of lymphocytes from the bloodstream into the secondary lymphoid organs, which is necessary for a successful immune response, occurs primarily within postcapillary venules that are characterized by high-walled endothelial cells. Lymphocyte adhesion to and extravasation at these sites is associated with the expression of specific lymphoid receptors for this specialized venule endothelium. We report here the molecular cloning from a baboon lymphoid cell line of a cDNA that encodes an adhesion receptor for HEV. The 362-amino acid protein encoded by this cDNA is not present in any of the data bases examined. The mature protein, resulting from the cleavage of a putative 20-amino acid signal peptide, has a calculated molecular mass of only 37 kDa, indicating that the 90-kDa cell surface protein is highly modified. The 342 amino acids, which lack any repeated sequences of significant length, encompass an extracellular domain (250 amino acids), a putative transmembrane domain (20 amino acids), and a cytoplasmic domain (72 amino acids).

Amino Acid Sequence↗