Search PubMed⌕ Search

Biomedical subjects

E C Butcher

Publications and source records attributed to E C Butcher.

At least 145 records · Page 8Linked to original sources
PubMed1991

The peripheral lymph node homing receptor, LECAM-1, is involved in CD18-independent adhesion of human neutrophils to endothelium.

The binding of polymorphonuclear granulocytes (PMN) to activated vascular endothelium is a crucial step in the recruitment of PMN to an inflammatory site. Studies employing cytokine-activated endothelium in culture have shown that PMN binding involves the CD18 family of leukocyte integrins, but also CD18-independent adhesion mechanism(s) on PMN that have not been defined. We unify here two previously disparate approaches to study cell adhesion events between endothelial cells and leukocytes. We show that antibodies to human LECAM-1, the peripheral lymph node homing receptor that is also expressed on PMN, partially inhibit the adhesion of human PMN not only to HEV in frozen sections of lymph node tissue, but also to cytokine-activated human umbilical vein endothelium in vitro. Inhibition with anti-LECAM-1 antibodies and anti-CD18 antibodies is additive. Furthermore, the anti-LECAM-1 antibodies inhibit the adhesion of CD18-deficient PMN to cytokine activated human endothelial cells. These findings indicate that LECAM-1 and CD18-mediated binding mechanisms are independent, and act coordinately or sequentially to mediate PMN attachment to cytokine activated endothelium.

CD18 Antigens↗
PubMed1991

Late treatment with anti-LFA-1 (CD11a) antibody prevents cerebral malaria in a mouse model.

CBA/Ca mice injected with Plasmodium berghei develop cerebral malaria (CM) characterized by ataxia and progressive paralysis leading to death 7-9 days after experimental infection. The development of cerebral symptoms is a function of the immune response in susceptible strains, and depends on cell-cell interactions involving T helper cells and mononuclear phagocytes. Here we ask whether antibodies to cell adhesion receptors of the immune system can influence the development of CM in this mouse model. When administrated on day 6 after infection, antibody to the leukocyte integrin leukocyte function-antigen-1 (LFA-1) but not antibodies to MAC-1, LECAM-1 (the MEL-14 antigen), alpha 4 integrin or ICAM-1 dramatically reduced the incidence of CM, leading to survival of most mice until the later onset of anemia. Anti-LFA-1 treatment did not result in a substantial decrease in the monocyte accumulation observed in cerebral vessels of susceptible mice. Its efficacy may be related to the broader roles of LFA-1 in cell-cell interactions important in the later pathogenic stages of the immune response to the parasite. Perturbation of immune cell function through interference with cell adhesion mechanisms may offer an important therapeutic tool in acute, life-threatening immune-mediated disorders.

Animals↗
PubMed1991

Dissection of murine lymphocyte-endothelial cell interaction mechanisms by SV-40-transformed mouse endothelial cell lines: novel mechanisms mediating basal binding, and alpha 4-integrin-dependent cytokine-induced adhesion.

Lymph node-derived endothelial cells were immortalized by infection with SV40 virus and subclones expressing the marker MECA 325 specific for high-endothelial venules (HEV) were selected. These transformed mouse endothelial (TME-) cell lines grow permanently without requirement for special growth factors. Staining of the selected clones with endothelium-specific antibodies and with anti-von Willebrand factor antiserum and uptake of acetylated low-density lipoprotein provide evidence for their endothelial origin. The vascular addressins identified by mAbs MECA 79 and MECA 367 on HEV are not detectable, indicating that the phenotype of the cells differs from that of HEV-type endothelium. The TME cells display a constitutive capacity to bind lymphocytes. An additional binding component is induced by treatment of the TME cells with TNF alpha. Antibodies against the homing receptor LECAM-1 (lectin-related leucocyte-endothelial cell adhesion molecule 1), alpha 4-integrins, vascular addressins, LFA-1, or ICAM-1 known to block lymphocyte interaction with particular types of HEV were unable to inhibit the basal adhesion to TME cells, indicating that a further binding mechanism in mice is displayed by this cell type. The adhesion component induced by TNF alpha is mediated by alpha 4-integrins since enhanced binding could be blocked by an antibody against mouse alpha 4 (lymphocyte-Peyer's patch adhesion molecule 1/2). TME cell lines therefore seem to be a useful model for the dissection and analysis of hitherto poorly characterized murine lymphocyte/endothelial cell interaction mechanisms.

Animals↗
PubMed1991

The human peripheral lymph node vascular addressin is a ligand for LECAM-1, the peripheral lymph node homing receptor.

The trafficking of lymphocytes from the blood and into lymphoid organs is controlled by tissue-selective lymphocyte interactions with specialized endothelial cells lining post capillary venules, in particular the high endothelial venules (HEV) found in lymphoid tissues and sites of chronic inflammation. Lymphocyte interactions with HEV are mediated in part by lymphocyte homing receptors and tissue-specific HEV determinants, the vascular addressins. A peripheral lymph node addressin (PNAd) has been detected immunohistologically in mouse and man by monoclonal antibody MECA-79, which inhibits lymphocyte homing to lymph nodes and lymphocyte binding to lymph node and tonsillar HEV. The human MECA-79 antigen, PNAd, is molecularly distinct from the 65-kD mucosal vascular addressin. The most abundant iodinated species by SDS-PAGE is 105 kD. When affinity isolated and immobilized on glass slides, MECA-79 immunoisolated material binds human and mouse lymphocytes avidly in a calcium dependent manner. Binding is blocked by mAb MECA-79, by antibodies against mouse or human LECAM-1 (the peripheral lymph node homing receptor, the MEL-14 antigen, LAM-1), and by treatment of PNAd with neuraminidase. Expression of LECAM-1 cDNA confers PNAd binding ability on a transfected B cell line. We conclude that LECAM-1 mediates lymphocyte binding to PNAd, an interaction that involves the lectin activity of LECAM-1 and carbohydrate determinants on the addressin.

Antigens, Surface↗
PubMed1991

Expression of vascular addressins and ICAM-1 by endothelial cells in the spinal cord during chronic relapsing experimental allergic encephalomyelitis in the Biozzi AB/H mouse.

The expression of adhesion molecules on central nervous system (CNS) endothelia was examined during chronic relapsing experimental allergic encephalomyelitis (CREAE) in the Biozzi AB/H mouse. Active disease episodes (acute and relapse) were associated with the up-regulation of MALA-2, the murine homologue of intercellular adhesion molecule-1 (ICAM-1), on CNS endothelia and the infiltration of ICAM-1-positive mononuclear cells. In addition, the high endothelial venule (HEV)-associated MECA-325 antigen was evident in perivascular lesions, particularly in relapsing disease. The peripheral lymph node HEV-associated vascular addressin defined by MECA-79 antibody was not detectable in the CNS during CREAE. However, the mucosal HEV addressin was evident in lesions, which ultrastructurally was found to be expressed on the surface of endothelial cells by immunoelectron microscopy. The expression of adhesion molecules, such as ICAM-1, may provide a means by which both the initial neuroantigen-specific and the subsequent antigen-non specific cells extravasate into the CNS. Such infiltration may induce the expression of the vascular addressins which may then provide a means of site-selective cellular recruitment leading to disease progression.

Animals↗
PubMed1990

Differential expression of homing-associated adhesion molecules by T cell subsets in man.

The ability of lymphocyte populations to recognize and bind high endothelial venules during homing into lymphoid tissues and sites of chronic inflammation is critically dependent on their expression of certain homing-associated adhesion molecules known as homing receptors (HR). In animal models, certain lymphocyte populations, particularly subsets of memory or previously activated lymphocytes, demonstrate tissue-selective homing behavior, and it has been hypothesized that differential expression of HR accounts for this selective migration. In this study, we analyzed expression of human HR--the Dreg 56/Leu 8-defined peripheral lymph node (PLN) HR (also known as LECAM-1), H-CAM (CD44), and alpha 4-integrins (CD49d; VLA-4)--among subsets of thymocytes and peripheral blood T cells to identify populations with differential homing potential. In the thymus, these three HR classes are differentially regulated relative to phenotypically defined maturational stages, but are all expressed on the mature, surface CD3high subset. In the peripheral blood, virgin T cells (LFA-3/CD58low) show uniform high expression of the PLN HR, uniform relatively low expression of H-CAM and alpha 4-integrin, and lack markers of tissue association--the mucosal and cutaneous lymphocyte associated Ag (MLA and CLA Ags) defined by mAb Ber ACT8 and HECA-452, respectively. In contrast, circulating memory T cells (LFA-3/CD58high) are bimodal with respect to PLN HR expression, show uniform high expression of H-CAM and alpha 4-integrin, and contain essentially all the CLA and MLA Ag-bearing T cells. The circulating skin-associated T cell subset (CLA Ag+; 10 to 15% of total T cells) is predominantly PLN HR+, and shows high levels of both the alpha 4- and beta 1-integrin chains. The distinct mucosa-associated T cell subset (MLA Ag+; 1 to 3% of peripheral blood T cells) is predominantly PLN HR-; and is alpha 4high, but beta 1low. These findings indicate the independent regulation of homing-associated adhesion molecules among populations of memory/previously activated T cells, and suggest that the expression patterns of these molecules contribute to, or perhaps determine, the tissue distribution of these subsets.

Adult↗
PubMed1990

Regulation and lectin activity of the human neutrophil peripheral lymph node homing receptor.

We characterize the nature and regulation of a human neutrophil cell surface antigen recognized by monoclonal antibodies (the DREG series) against a human lymphocyte peripheral lymph node homing receptor. Human neutrophils express high levels of the DREG antigen, whose expression is downregulated after treatment with phorbol myristate acetate, or the chemotactic factors C5a and FMLP. Interestingly, C5a treatment also downregulated the monocyte DREG antigen, but had no effect on expression of the lymphocyte molecule. Within 3 minutes after treatment with C5a, greater than 80% of neutrophil DREG antigen expression is lost, and essentially the molecule is completely removed from the cell surface by 5 minutes. The human neutrophil DREG antigen is 10 Kd larger than the lymphocyte molecule. These features are similar to those of the mouse neutrophil MEL-14 antigen (murine peripheral lymph node homing receptor). The mannose-6-phosphate rich phosphomannan (PPME) binds human lymphocytes via the DREG antigen. PPME also binds neutrophils, but little difference in binding is seen between unactivated and activated cells. We show that PPME binding to unactivated neutrophils is mediated primarily by a cation- and DREG antigen-dependent mechanism, whereas activated neutrophil-PPME binding is DREG antigen- and cation-independent, and may be due to the translocation of lysosomal mannose-6-phosphate receptors to the cell surface. The DREG antibodies offer powerful tools for analyzing the role of homing receptors in human neutrophil-endothelial cell interactions, and also may prove valuable in the clinical assessment of neutrophil activation.

Antibodies, Monoclonal↗
PubMed1990

Hematopoietic progenitor cell expression of the H-CAM (CD44) homing-associated adhesion molecule.

We explored the expression of a lymphocyte homing-associated cell adhesion molecule (H-CAM, CD44) on hematopoietic progenitors. We demonstrate that immature myeloid and erythroid leukemic cell lines stain intensely with monoclonal antibodies Hermes-1 and Hermes-3, which define distinct epitopes on lymphocyte surface H-CAM, a glycoprotein involved in lymphocyte interactions with endothelial cells. Using fluorescence-activated cell sorting (FACS), human marrow cells were fractionated into Hermeshi, Hermesmed, and Hermeslo populations according to the expression of both the Hermes-1 and Hermes-3 epitopes. Granulocyte-macrophage colony-forming unit and erythroid burst-forming unit precursors were found predominantly in the brightly positive fractions. Two-color FACS analysis confirmed that the My10 (CD34) positive populations of cells in bone marrow, which contain most of the progenitor cell activity, are brightly positive for Hermes-1. Finally, we demonstrate that among bone marrow cells, the highest levels of H-CAM are expressed on myeloid and erythroid progenitors as well as mature granulocytes and lymphocytes. Thus we provide evidence that molecules related or identical to the H-CAM homing receptor are expressed on marrow progenitor cells. H-CAM may contribute to progenitor cell interactions with marrow endothelial and stromal cell elements important to the maintenance and regulation of hematopoiesis.

Antibodies, Monoclonal↗
PubMed1990

The rat B cell system: the anatomical localization of flow cytometry-defined B cell subpopulations.

Two-color flow cytometrical (FCM) analysis of rat peripheral lymphoid organs shows two distinct IgM/IgD-defined B cell subpopulations, similar to those of the mouse: a major population of cells expressing little IgM and high levels of IgD (population I) and a minor population of cells expressing high levels of IgM but little IgD (population III). In peripheral lymphoid organs population III cells are mainly found in spleen where they represent about 25% of the B cells; population III cells are almost absent from lymph nodes and Peyer's patches. In adult bone marrow and in neonatal spleen the majority of IgM/IgD-defined B cells (greater than 70%) are population III cells, similar to what is observed in the mouse. In contrast with mice, only a low proportion of the cells (1%) recovered from the peritoneal cavity are B cells, and most of them belong to population I. Previously defined monoclonal antibodies (HIS22 and HIS24) to B cell forms of the leukocyte common antigen (CD45R) in combination with staining for surface IgM and surface IgD demonstrates a further heterogeneity of rat B cells by three-color FCM analyses. HIS22 labels most population I cells; population III cells and a small subset (about one third) of population I express only very low levels of the HIS22 determinant. HIS24 reacts with population I cells and subdivides population III into two subsets: about one third of splenic population III cells are brightly stained with this antibody whereas fluorescence of the remaining two-thirds is lower. The HIS24bright population III cells likely are newly formed B cells since cells with this phenotype are the predominant surface Ig population found in adult bone marrow and neonatal spleen. In tissue sections of lymphoid organs, HIS22- and HIS24-positive cells are mainly found in lymphoid follicles; splenic marginal zones are almost unstained. Combining immunohistological analysis with the FCM data, we therefore conclude that the small follicular B cells are in population I and marginal zone B cells are found in the HIS24dull population III. The in situ localization of HIS24bright population III cells and the HIS22dull population I cells is not clear.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Expression of low levels of peripheral lymph node-associated vascular addressin in mucosal lymphoid tissues: possible relevance to the dissemination of passaged AKR lymphomas.

Lymphoid tumors display a wide variety of growth patterns in vivo, from that of a solitary extralymphoid tumor, to a general involvement of all lymphoid organs. Normal lymphocytes are uniquely mobile cells continuously recirculating between blood and lymph throughout much of their life cycle. Therefore, it is reasonable to propose that disseminating malignant lymphocytes may express recirculation characteristics or homing properties consistent with that of their normal lymphoid counterparts. Trafficking of lymphocytes involves the expression and recognition of both lymphocyte homing receptors and their opposing receptors on endothelium, the vascular addressins. These cell surface elements direct the tissue-selective localization of lymphocyte subsets in vivo into organized lymphoid organs and sites of chronic inflammation where specific binding events occur between lymphocytes and the endothelium of specialized high endothelial venules (HEV). In a recent murine study of 13 lymphoma lines, we found that lymphomas that bind well to high endothelial venules, in the Stamper-Woodruff in vitro assay (an assay of lymphocyte binding to venules in frozen sections of peripheral lymph nodes or Peyer's patches), spread hematogenously to all high endothelial venule bearing lymphoid organs, whereas non-binding lymphomas did not. In some cases lymphomas that bound with a high degree of selectivity to peripheral lymph node (PLN) high endothelial venules exhibited only limited organ preference of metastasis, involving the mucosal lymphoid organs Peyer's patches (PP) in addition to the peripheral lymph nodes of adoptive recipients. Here we demonstrate that Peyer's patch high endothelial venules express a low but functional level of peripheral lymph node addressin (MECA-79) that can be recognized by lymphomas expressing the peripheral lymph node homing receptor (MEL-14 antigen).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Identification of mRNA that encodes an alternative form of H-CAM(CD44) in lymphoid and nonlymphoid tissues.

The cluster of differentiation 44 (CD44), hereafter referred to as H-CAM(CD44), represents a novel class of polymorphic (Mr 80,000-215,000) cell adhesion molecules that are involved in cell-cell and cell-matrix adhesion events in a variety of organ systems. We report the detection of distinct mRNAs, in both hematopoietic and nonhematopoietic human cell lines, that encode H-CAM(CD44) with different cytoplasmic domains. Genomic Southern blot analyses indicate that the exons encoding these two cytoplasmic domains are located on the same approximately 16 kilobase (kb) Eco RI restriction fragment. Restriction endonuclease and Southern blot analyses performed on polymerase chain reaction (PCR) amplification copies of these mRNAs confirm that their sequences correspond with previously reported cDNA sequences. A consensus splice donor site which is conserved in human, baboon, and mouse mRNAs that encode a molecule with an elongated cytoplasmic domain (H-CAM-L) is utilized to generate a distinct but low-abundance mRNA species that encodes H-CAM(CD44) with a truncated cytoplasmic domain of only three amino acids (H-CAM-S). Estimations of the relative abundance of these mRNA species in B-lymphoblastoid cells using the PCR amplification technique exhibit average H-CAM-L/H-CAM-S ratios ranging between 100 and 200. Therefore, H-CAM (CD44)-mediated adhesive events may be regulated through a differential capacity of H-CAM-L and H-CAM-S to interact with the cytoskeleton and to participate in intracellular signaling events.

Base Sequence↗
PubMed1990

Identification of a human peripheral lymph node homing receptor: a rapidly down-regulated adhesion molecule.

Lymphocyte migration to lymphoid organs involves organ-specific homing receptors. The mouse peripheral lymph node homing receptor, defined by the MEL-14 monoclonal antibody (mAb), is a lectin-like cell surface protein, which is rapidly down-regulated upon cell activation with phorbol 12-myristate 13-acetate. We have raised mAbs against rapidly shed molecules released from the cell surface of activated human leukocytes. Five mAbs, DREG-55, -56, -110, -152, and -200, define an 80- to 85-kDa molecule involved in human lymphocyte recognition of peripheral lymph node (PLN) high endothelial venules (HEVs). The DREG-56 mAb specifically inhibits greater than 90% of binding of human lymphocytes to HEVs within frozen sections of peripheral but not mucosal lymphoid tissue. Furthermore, the gp80 antigen is expressed on lymphoid cell lines that are capable of binding to PLN HEVs. The DREG-56 mAb also inhibits lymphocyte binding of the phosphomannan monoester core from Hansenula hostii Y-2448, an activity associated with human and mouse lymphocyte recognition of PLN HEVs. Finally, all five DREG mAbs specifically stain COS cells transfected with LAM-1 cDNA, a putative human homologue of mouse MEL-14 antigen. These results demonstrate that the DREG mAbs define a human lymphocyte homing receptor for PLN HEVs and indicate that this human antigen is homologous to the MEL-14-defined murine lymphocyte homing receptor.

Animals↗
PubMed1990

The hyaluronate receptor is a member of the CD44 (H-CAM) family of cell surface glycoproteins.

The present study was undertaken to determine the relationship between the hyaluronate receptor and CD44 (H-CAM), cell-surface glycoproteins of similar molecular weights that have been implicated in cell adhesion. In initial experiments, a panel of monoclonal antibodies directed against CD44 were tested for their ability to cross react with the hyaluronate receptor. These antibodies immunoprecipitated [3H]hyaluronate binding activity from detergent extracts of both mouse and human cells, indicating that the hyaluronate receptor is identical to CD44. In addition, one of these antibodies (KM-201 to mouse CD44) directly blocked the binding of labeled hyaluronate to the receptor and inhibited hyaluronate dependent aggregation of SV-3T3 cells. CD44 has also been implicated in lymphocyte binding to high endothelial venules during lymphocyte homing. Interestingly, the monoclonal antibody Hermes-3, which blocks lymphocyte binding to the high endothelial venules of mucosal lymphoid tissue, had no effect on the binding of labeled hyaluronate. Furthermore, the binding of lymphocytes to high endothelial cells of lymph nodes and mucosal lymphoid tissue was not significantly affected by treatment with agents that block the binding of hyaluronate (hyaluronidase, excess hyaluronate and specific antibodies). Thus, CD44 appears to have at least two distinct functional domains, one for binding hyaluronate and another involved in interactions with mucosal high endothelial venules.

Animals↗
PubMed1990

A unique phenotype of skin-associated lymphocytes in humans. Preferential expression of the HECA-452 epitope by benign and malignant T cells at cutaneous sites.

It has been proposed that the skin is a functionally unique compartment of the immune system, although little direct evidence supporting this hypothesis has been presented. Here we show that lymphocyte populations at cutaneous sites can be differentiated from otherwise similar populations at noncutaneous sites by their preferential expression of an epitope defined by the MAb HECA-452. This MAb recognizes a predominantly 200-kd cell-surface glycoprotein present on about 16% of peripheral blood T cells, including both CD4+ and CD8+ T cells (17% and 11% HECA-452+, respectively), as well as TCR-delta-bearing T cells (32%+). Most thymocytes (99%) lacked HECA-452 antigen expression, and essentially all the HECA-452+ peripheral blood T cells were found in the adhesion molecule high, CD45R low putative memory cell subset, findings suggesting that HECA-452 expression develops peripherally as a consequence of antigenic stimulation. However, the HECA-452 antigen is not a conventional activation antigen because it was not upregulated with mitogen stimulation of peripheral blood T cells. Most significantly, among 54 diverse specimens of normal/reactive lymphoid tissues and sites of chronic inflammation, there was a clear association of lymphocyte HECA-452 expression and cutaneous location. In extracutaneous sites (n = 38) only about 5% of lymphocytes within the T-cell areas of these tissues expressed this antigen, whereas in inflammatory skin lesions (n = 16), 85% were HECA-452+. The association of HECA-452 expression and cutaneous location was also seen in a series of T-cell lymphomas. The malignant cells of 16 of 18 cases of epidermotropic (patch/plaque) stage mycosis fungoides were HECA-452+, as well as 2 of 7 nonmycosis fungoides peripheral T-cell lymphomas in skin. In contrast, this antigen was not expressed in thymic (lymphoblastic) lymphomas (n = 14), nonepidermotropic (tumor) stage mycosis fungoides (n = 5), and noncutaneous peripheral T-cell lymphomas (n = 15). Among lymphocytes, the preferential expression of the HECA-452 determinant by cutaneous T cells supports the hypothesis that the skin constitutes a immunologically unique lymphoid tissue and suggests that this molecule may play a role in either lymphocyte homing to skin or in lymphocyte interactions with the epidermis.

Cell Line↗
PubMed1989

Function and regulation of the neutrophil MEL-14 antigen in vivo: comparison with LFA-1 and MAC-1.

The CD11/18 (LFA-1, Mac-1) molecules participate in neutrophil adhesion to cultured endothelium in vitro and are critical for effective neutrophil localization into inflamed tissues in vivo. More recently, the MEL-14 Ag, which was first defined as a lymphocyte homing receptor, has also been implicated in inflammatory neutrophil extravasation. Here we compare the regulation and function of these adhesion molecules on neutrophils during the in vivo inflammatory response. The MEL-14 Ag is expressed at high levels on bone marrow and peripheral blood neutrophils, but is lost on neutrophils isolated from the thioglycollate-inflamed peritoneal cavity. In contrast, Mac-1 is up-regulated on inflammatory neutrophils and little change is seen in the level of LFA-1 expression. In vitro activation of bone marrow neutrophils with PMA or leukotriene B4 results in a dose dependent increase in Mac-1 and decrease in MEL-14 Ag expression within 1 h after treatment, thus reflecting what is found during inflammation in vivo. Neutrophils activated in vitro or in vivo (MEL-14Low, Mac-1Hi) do not home to inflammatory sites in vivo, correlating with the loss of the MEL-14 Ag and the increased Mac-1 expression. Anti-LFA-1, anti-Mac-1, or MEL-14 antibody given i.v. suppress neutrophil accumulation within the inflamed peritoneum (38%, 30%, and 37% of medium control, respectively) without affecting the levels of circulating neutrophils. However, when FITC-labeled cells are precoated with the mAb and injected i.v., only MEL-14 inhibits extravasation into the inflamed peritoneum (25% of medium control). Finally, in ex vivo adhesion assays of neutrophil binding to high endothelial venules in inflamed-lymph node frozen sections MEL-14 inhibits greater than 90%. anti-LFA-1 20 to 30% and anti-Mac-1 less than 10% of the binding of bone marrow neutrophils to inflamed-lymph node high endothelial venules. These results confirm that both the MEL-14 antigen and Mac-1/LFA-1 are important in neutrophil localization to inflamed sites in vivo, but suggest that their roles in endothelial cell interactions are distinct.

Animals↗
PubMed1989

Molecular cloning and expression of Pgp-1. The mouse homolog of the human H-CAM (Hermes) lymphocyte homing receptor.

Mouse phagocytic glycoprotein-1 (Pgp-1; Ly-24) is a 95-kDa glycoprotein of unknown function that has served as an important T cell/leukocyte differentiation marker. Recent work has suggested that it may be related to a human 85- to 95-kDa glycoprotein (termed variously the Hermes Ag/lymphocyte homing receptor, ECMRIII, P80, and CD44) that is involved in lymphocyte binding to high endothelial venules in the process of lymphocyte homing, and has been implicated in other cell adhesion events. The widespread expression of this molecular class in diverse organ systems suggests a broad role in cellular adhesion, and has led to the unifying designation homing-cellular adhesion molecule (H-CAM). By using human H-CAM cDNA probes, we have isolated a full-length cDNA for the mouse homolog. Comparison of the human and mouse sequences reveals that an N-terminal domain homologous to cartilage proteoglycan core and link proteins, as well as the C-terminal transmembrane and cytoplasmic sequences, are highly conserved (89% and 86% identity, respectively). In contrast, a proximal extracellular domain thought to serve as a target for O-glycosylation and chondroitin sulfate attachment has undergone substantial divergence (only 42% identity). Transient expression of the cDNA in CHO cells followed by immunologic staining confirms that this mouse H-CAM cDNA encodes Pgp-1.1, one of two known Pgp-1 alloantigens.

Amino Acid Sequence↗