Biomedical subjects

M Patarroyo

Publications and source records attributed to M Patarroyo.

At least 37 records · Page 2Linked to original sources

PubMed1995

Escherichia coli induces transuroepithelial neutrophil migration by an intercellular adhesion molecule-1-dependent mechanism.

During bacterial infections at mucosal sites, neutrophils migrate to the mucosa and cross the epithelial barrier. We have examined neutrophil migration across Escherichia coli-stimulated uroepithelial cell layers in an attempt to more fully understand this process. Stimulation of uroepithelial cells with E. coli or interleukin-1 alpha (IL-1 alpha) induced transepithelial neutrophil migration in a time- and stimulant dose-dependent manner. Uroepithelial cell lines and nontransformed uroepithelial cells expressed intercellular adhesion molecule-1 (ICAM-1) but not ICAM-2, E-selectin, or P-selectin. Epithelial ICAM-1 expression was enhanced after stimulation with E. coli or IL-1 alpha. Anti-ICAM-1 antibody reduced transepithelial neutrophil migration by 61 to 85%, indicating that neutrophils bound ICAM-1 on the epithelial surface. Antibodies to CD18 and CD11b reduced migration by 70 to 79%, suggesting that CD11b/CD18 (Mac-1) was acting as the neutrophil receptor for ICAM-1 in this process. Anti-CD11a antibodies had no effect on neutrophil migration. In conclusion, E. coli induced ICAM-1- and Mac-1-dependent transepithelial neutrophil migration. Previous studies have shown that urinary tract epithelial cells secrete IL-8 when exposed to E. coli or IL-1 alpha. These observations suggest that epithelial cells play an active role in neutrophil migration during urinary tract infections.

CD18 Antigens↗

PubMed1995

Extracellular matrix proteins and integrin receptors in reactive and non-reactive lymph nodes.

The extracellular matrix (ECM) proteins collagen I, III and IV, laminin, fibronectin, vitronectin, thrombospondin, tenascin and their integrin receptors of the beta 1 and beta 3 subfamilies showed characteristic patterns of distribution in different compartments of non-reactive and reactive lymph nodes (human and monkey). This was particularly evident during development of germinal centres. Thus, ECM proteins (collagens, laminin, fibronectin and tenascin) were abundant in the interfollicular (T-cell rich) compartments of non-reactive as well as reactive lymph nodes. In primary follicles, collagen I, III and fibronectin were expressed but displaced by the expanding germinal centre during the formation of secondary follicles in reactive lymphoid tissues. The integrin subunits were mainly associated with endothelial cells and lymphoid cells in interfollicular areas, but were absent or only poorly expressed in primary as well as secondary follicles. Evidently the expression of ECM components and their integrin receptors is markedly down-regulated in the reactive, highly proliferative germinal centres.

Animals↗

PubMed1994

Regulated expression of integrins and other adhesion molecules during differentiation of monocytes into macrophages.

Monocyte/macrophages adhere to cells (lymphocytes, vascular endothelial and other cell types) and to extracellular matrix components (fibronectin and laminin) by using specific cell surface adhesive structures. In the present study we have analyzed expression of integrins, immunoglobulin (Ig)-related, selectins, and other adhesion molecules on blood monocytes, in vitro differentiated macrophages (ivMs), and alveolar macrophages (AMs), obtained from healthy nonsmokers by bronchoalveolar lavage (BAL). We have also investigated expression of adhesion molecules on myelomonocytic cell lines HL-60, THP-1, KG-1, and U937 before and after tetradecanoyl phorbol acetate (TPA)-induced differentiation. With regard to the integrin family, monocytes expressed beta 1 (CD29), alpha 4, alpha 5, alpha 6, beta 2 (CD18), CD11a, CD11b, and CD11c subunits, but not alpha V (CD51). Some reactivity with mAbs against the platelet antigens CD41b (IIb) and CD61 (beta 3) was detected. The Ig-related molecules CD54 (ICAM-1), ICAM-2, and CD58 (LFA-3) were expressed, as well as L-selectin and the carbohydrate ligands Le(x) (CD15) and sialyl Le(x). Immunolabeling for the structurally unrelated molecules CD44 and CD36 was strongly positive. In comparison to monocytes, AMs showed much lower expression of alpha 4, alpha 6, beta 2, CD11a, CD11b, L-selectin, Le(x), and sialyl Le(x). Moreover, ICAM-2 and CD36 were practically absent whereas expression of alpha 3, but not of CD11c, was higher. Similar results were obtained with ivMs. All four myelomonocytic cell lines showed down-regulation of alpha 4 and up-regulation of CD11c after TPA treatment. These findings indicate that maturation of monocytes into macrophages is accompanied by characteristic changes in adhesion molecule expression. The particular array of adhesion molecules on monocytes and macrophages may account for differences in the functional properties of these cells.

Antigens, CD↗

PubMed1994

Adhesion molecules mediating recruitment of monocytes to inflamed tissue.

Three families of cell-surface proteins are largely responsible for the adherence of leukocytes to cells and matrices: integrins, immunoglobulin (Ig)-related molecules and selectins. Blood monocytes express beta 1 integrins VLA-4, -5 and -6 and beta 2 integrins CD11a/CD18, CD11b/CD18 and CD11c/CD18. These cells also express the Ig-related molecules ICAM-1, -2 and -3, ligands for the beta 2 integrins. In addition, monocytes express L-selectin and the oligosaccharides Lex and sialyl Lex, ligands for the endothelial selectins E- and P-. In vitro studies with blocking antibodies have identified adhesion molecules participating in the adherence of monocytes to one another, to T lymphocytes and to vascular endothelial cells. These antibodies also block adhesion-dependent monocyte activities, such as cytotoxicity of tumor cells, antigen presentation, phagocytosis of large particles, induction of cytokine secretion, formation of multinucleated giant cells and HIV-induced syncytium formation. In vivo studies in animals have demonstrated participation of L-selectin and CD11b/CD18 in monocyte accumulation in inflamed peritoneum. Moreover, treatment with anti-CD11b antibodies potentiates primary listeriosis and inhibits the macrophage recruitment and granuloma formation, and anti-CD18 antibodies block ear swelling in Mycobacterium tuberculosis-immunized animals following challenge with PPD. Adhesion molecules may also play key roles in the pathogenesis of tuberculosis and AIDS.

Acquired Immunodeficiency Syndrome↗

PubMed1994

Expression of adhesion molecules CD11/CD18 (Leu-CAMs, beta 2-integrins), CD54 (ICAM-1) and CD58 (LFA-3) in B-chronic lymphocytic leukemia.

Cell adhesion molecules (CAMs) are cell surface proteins with unique specificities that allow intercellular adhesion. The importance of CAMs for normal lymphocyte growth and differentiation is underscored by the association between neoplastic disease states and abnormal CAM expression. In the present study we analysed the cell surface expression of several CAMs on peripheral blood lymphocytes from patients with progressive chronic lymphocytic leukemia of B-cell type (B-CLL) (n = 21) and stable monoclonal B-lymphocytosis of undetermined significance (B-MLUS) (n = 20). The CAM expression was analysed on the B-cell clone and on normal T- and NK-cell populations separately using monoclonal antibodies (MAbs). A phorbol ester-induced lymphocyte aggregation assay and blocking MAbs were also used. The B-cell clone in B-CLL expressed ICAM-1 (CD54) more frequently and at a higher density than in B-MLUS. The brightest CD54 expression was noted in patients with prominent lymphadenopathy and/or splenomegaly. The beta 2 integrin CD11a (Leu-CAMa, LFA-1) was detected on some B-cell clones and seemed to relate to tissue localization of the disease. T and NK cells showed a low expression of CD11a in B-CLL patients, while in B-MLUS a high proportion of non-clonal cells coexpressed CD11a with a high staining intensity. The relative numbers of both CD18+ as well as CD2+ cells showed a positive correlation with phorbol ester induced cell aggregation in B-MLUS patients (p < 0.05). The aggregation was blocked by adding MAbs against CD18 in most cases but to a greater extent in B-CLL. These results extend and corroborate our earlier findings on surface phenotypic characteristics of clonal and non-clonal lymphocytes in different clinical subtypes of B-CLL. CAM expression on the monoclonal lymphocytes may play a role in their interaction with regulatory immune cells and their tissue localization.

Aged↗

PubMed1993

Expression of integrins and other adhesion molecules on NK cells; impact of IL-2 on short- and long-term cultures.

We have investigated, using flow cytometry, the expression of 19 adhesion molecules on fresh and IL-2-activated NK cells. The study included beta 1, beta 2 and beta 3 integrins, CD2, CD54 and CD58 (belonging to the immunoglobulin superfamily), and CD44 and L-selectin (homing receptors). alpha 1 and alpha 2 of the beta 1 integrins were non-existent and alpha 3 was weak on freshly isolated NK cells, but their expression increased after 4 weeks in culture with IL-2. On the other hand, some down-regulation of alpha 4 and alpha 5 and disappearance of alpha 6 was detected. CD 11a/CD18 was upregulated by IL-2, whereas CD11b-c/CD18 were down-regulated. As a novel finding we detected beta 3 on IL-2-activated T and NK cells. CD2, CD44, CD54 and CD58 were increased by IL-2 but L-selectin was strongly down-regulated on the long-term-activated NK cells. Although IL-2-activated lymphocytes are potent tumor-lysing killer cells in vitro and therefore a potential modality in cancer treatment, the IL-2 induced changes in lymphocyte adhesion molecule expression may also lead to undesired effects, such as altered untargeted distribution and compromised migratory capacity.

Cell Adhesion Molecules↗

PubMed1993

Adhesion molecule expression on cerebrospinal fluid T lymphocytes: evidence for common recruitment mechanisms in multiple sclerosis, aseptic meningitis, and normal controls.

The expression of T-cell surface antigens was investigated in the cerebrospinal fluid (CSF) and peripheral blood of 11 patients with multiple sclerosis, 6 patients with aseptic meningitis, and 16 healthy subjects. A panel of monoclonal antibodies to adhesion and activation proteins was used in combination with an anti-CD3 antibody in dual-color flow cytometry. The problem of low cell numbers in the CSF from normal individuals was overcome by use of a modified staining procedure in microtiter plates, enabling analysis of as few as 5,000 cells. The majority of T cells in the CSF of the three patient groups exhibited the phenotype of memory cells (CD45RO+). CSF T cells also expressed significantly higher levels of several adhesion and activation molecules, including very late activation (VLA) antigens 3 through 6, lymphocyte function-associated (LFA) antigen 1, LFA-3, CD2, CD26, and CD44. Comparison between the different categories revealed that peripheral blood T cells from patients with multiple sclerosis expressed significantly lower amounts of the VLA integrins 4 and 5 as well as their common beta subunit CD29, compared with normal control subjects. No differences between patients with multiple sclerosis and control subjects could, however, be seen regarding the distribution of memory/naive cells or CD4+/CD8+ cells in peripheral blood. Our data support a hypothesis that memory T cells with a high expression of several adhesion molecules are selectively recruited to the central nervous system compartment, under both pathological and normal conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

Chemotaxins inhibit neutrophil adherence to and transmigration across cytokine-activated endothelium: correlation to the expression of L-selectin.

Non-activated neutrophils strongly adhere to cytokine-activated human umbilical vein endothelial cells (HUVE). However, activation of neutrophils by different chemotactic mediators led to potent inhibition of this endothelial-dependent interaction. For different formylated peptides, concentrations leading to maximal adherence inhibition coincided with those known for inducing maximal chemotactic migration of neutrophils. In terms of maximal adherence inhibition, a rank list was found in the order of N-formyl-Met-Leu-Phe > C5adesArg > interleukin-8 > C5a > or = leukotriene B4, whereas platelet-activating factor, and lipopolysaccharide showed no inhibition. This rank order was congruent to that of down-regulation of neutrophil L-selectin detected by the monoclonal antibody Leu-8. Moreover, the dose-dependent increase of neutrophil adherence inhibition corresponded to the loss of L-selectin expression. Concentrations higher than that required for maximal inhibition led to a dose-dependent decrease of inhibition, which was accompanied by increasing expression of neutrophil CD11/CD18. In contrast to the capacity of non-activated neutrophils to migrate across interleukin-1-activated HUVE monolayers, transmigration was significantly impaired after chemotactic activation.

Antigens, CD↗

PubMed1993

Regulation of lymphocyte aggregation and proliferation through adhesion molecule CD54 (ICAM-1).

The effect of two mouse mAb (LB-2 and G1B2) against human CD54 (intercellular adhesion molecule-1, ICAM-1) in lymphocyte aggregation and proliferation systems was investigated. The LB-2 mAb, but not G1B2, inhibited phorbol ester-induced aggregation of B lymphoblastoid cells. In addition, LB-2, but not G1B2, induced aggregation and proliferation of peripheral blood mononuclear cells (PBMC) in cultures containing FCS. The Fab fragment of LB-2 always (10/10 donors) induced proliferation while the intact mAb was active in 3/11 donors. When cultures contained human serum (HS), LB-2 and its Fab fragment induced proliferation in 1/9 and 1/4 donors, respectively. Addition of HS to FCS cultures inhibited proliferation induced by LB-2 Fab, indicating the presence of an inhibitory factor in human serum. Addition of anti-CD18 mAb to cultures stimulated by LB-2 Fab caused partial inhibition of proliferation but did not prevent aggregate formation. A combination of anti-CD18 and anti-CD29 mAb resulted in a nearly complete inhibition of proliferation but did not inhibit aggregate formation. In these experiments it was found that the anti-CD29 mAb 4B4 in itself induced cell aggregation of PBMC and enhanced aggregation induced by the anti-CD3 mAb OKT3. Both LB-2 and G1B2 showed significant inhibition (> 60%) of proliferation when human PBMC were stimulated by the antigen PPD in the presence of HS, but not when stimulated by staphylococcal enterotoxin A (SEA) or IL-2. This study describes two mAb against separate epitopes on CD54 which are differentially involved in cell aggregation or induction of proliferation but are of similar importance in antigen-specific responses. Furthermore, the new finding that the LB-2 mAb or its Fab fragment can induce cell aggregation and proliferation defines a signaling function of CD54 which may work independent of crosslinking or costimulation.

Animals↗

PubMed1993

Mononuclear leukocytes exposed to oxidized low density lipoprotein secrete a factor that stimulates endothelial cells to express adhesion molecules.

In animals fed a hypercholesterolemic diet, development of atherosclerosis is preceded by attachment of mononuclear leukocytes to the arterial endothelium. Early lesions begin to develop as monocytes migrate into the intima and ingest lipids. A major part of these lipids is believed to be derived from oxidatively modified low density lipoprotein (LDL). In the present study we demonstrate that human mononuclear leukocytes exposed to low concentrations of copper-oxidized LDL secrete one or several factors that stimulate the expression of intercellular adhesion molecule-1 (ICAM-1, CD54), vascular cell adhesion molecule (VCAM-1) and endothelial selectin (E-selectin-1, ELAM-1), whereas native LDL was found to be without effect. Exposure of endothelial cells to non-conditioned medium containing oxidized LDL did not influence the expression of adhesion molecules. Incubation of endothelial cells with conditioned medium from mononuclear cells grown in the presence of oxidized LDL also resulted in a three-fold increase in the binding of monocytoid U937 cells. The present findings suggest that mononuclear leukocytes exposed to oxidatively modified LDL in early atherosclerotic lesions may stimulate the recruitment of other leukocytes by secreting cytokines which induce the expression of adhesion molecules on the endothelium.

Cell Adhesion↗

PubMed1992

Involvement of beta 2-integrins in the migration of human natural killer cells.

Human large granular lymphocytes with the NK cell phenotype (CD16+ or CD56+CD3-) were greatly enriched among the cells which migrated spontaneously through untreated or albumin-coated, 3-microns pore size polycarbonate filters for 1 to 8 h. Three days of rIL-2 treatment (300 IU/ml) and 3 to 5 wk of rIL-2 treatment (100 IU/ml) generated a 2.7 +/- 0.9-fold and 5.6 +/- 0.8-fold increase in cell migration, respectively. The adhesion and subsequent migration of freshly isolated NK cells was mainly mediated by CD11b/CD18, because migration could be inhibited by 80 +/- 8% anti-CD11b (Mac-1) antibodies but not with antibodies against CD11a (LFA-1) or CD11c (p150,95), the other alpha-chains of the beta 2-integrins. After rIL-2 activation, however, CD11a/CD18 was the major receptor utilized in migration, inasmuch as anti-CD11a antibody caused a 69 +/- 8% reduction in the number of migrated cells. Anti-CD11b antibody decreased migration by 43 +/- 12%, and together these antibodies inhibited migration by 82 +/- 7%. Anti-CD11a alone did not have any effect on adhesion, but CD11a/CD18 cooperated in the adhesion because anti-CD11b decreased adhesion by 40 +/- 11% and together these antibodies inhibited adhesion by 74 +/- 6%. The ability of large granular lymphocytes to rapidly utilize beta 2-integrins and unidentified ubiquitous ligands for binding and migration may be significant for their capacity to function in the first line of immune defense under highly variable conditions.

Antibodies, Monoclonal↗

PubMed1992

Migration of recombinant IL-2-activated T and natural killer cells in the intercellular space of human H-2 glioma spheroids in vitro. A study on adhesion molecules involved.

The migration of rIL-2-activated T and NK cells into the intercellular space of glioma tissue was studied using multicellular spheroids grown from the human H-2 glioblastoma cell line as targets. Lymphocytes of all analyzed subtypes migrated into the spheroids, but CD56+ cells were particularly migratory. Lymphocytes and the H-2 tissue expressed adhesion molecule subunits for the following potential cell-cell or cell-matrix interactions: alpha 3 beta 1 (VLA-3) to fibronectin, laminin, and collagen; alpha 4 beta 1 (VLA-4) and alpha 5 beta 1 (VLA-5) to fibronectin; alpha 6 beta 1 (VLA-6) to laminin; alpha 4 beta 1 to VCAM-1; alpha L beta 2 (Leu-CAMa/LFA-1) to CD54 (ICAM-1); CD44 to fibronectin, collagen, laminin, hyaluronate; CD2 to CD58 (LFA-3); and CD56 (N-CAM) to CD56. In the H-2 tissue, CD54 and VCAM-1 were expressed as a gradient. The expression of CD54 was weak in the peripheral zone and the expression was stronger in the quiescent deeper zone, whereas the distribution of VCAM-1 showed an inversed pattern. The low expression of CD54 was up-regulated along the frontier of migrating lymphocytes. The migration was almost totally prevented by the anti-CD18 (beta 2) mAb IB4 and TS1/18, and also strongly inhibited by the anti-CD54 mAb LB-2. Instead, mAb known to inhibit the binding of beta 1 integrins to fibronectin were not significantly inhibitory. However, a combination of the GPEILDVPST and GRGDS peptides, which compete for the binding of alpha 4 beta 1 and alpha 5 beta 1 to fibronectin and may also affect other adhesion systems, partially prevented migration.

Amino Acid Sequence↗

PubMed1992

Expression of integrins and other adhesion molecules in Epstein-Barr virus-transformed B lymphoblastoid cells and Burkitt's lymphoma cells.

Lymphocytes adhere to cells or extracellular matrices to perform functions relating to cytotoxicity, extravasation and tissue localization, as well as modulation of lymphocyte growth and maturation. This adherence is mainly mediated by 3 families of cell-surface adhesion molecules: integrins, immunoglobulin-related molecules and selectins. Since variations in the degree of adherence may affect the pathophysiology of lymphoproliferative disorders, the expression of a large number of adhesion molecules was analysed on Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs), and on EBV-positive or EBV-negative Burkitt's lymphoma (BL) lines, by immunofluorescence flow cytometry and immunoprecipitation with monoclonal antibodies. With regard to the beta 1, beta 2 and beta 3 integrin subfamilies, LCLs strongly expressed CD49d/CD29 (VLA-4), CD11a/CD18 (Leu-CAMa, LFA-1) and CD51/CD61 (vitronectin receptor). These cells also abundantly expressed CD54 (ICAM-1) and CD58 (LFA-3) as well as the "homing receptors" L-selectin (LECAM-1) and CD44. BL lines had considerably lower amounts of VLA-4 than LCLs, and ICAM-1 was expressed only by some of the tumor lines. All other adhesion molecules were absent or minimally expressed in the BL cells.

Antibodies, Monoclonal↗

PubMed1992

Integrins and other adhesion molecules on lymphocytes from synovial fluid and peripheral blood of rheumatoid arthritis patients.

Cell and matrix adhesion of lymphocytes participates in homing, migration and accumulation of these cells in inflamed tissues as well as in the generation of immune and inflammatory responses. In inflamed joints of rheumatoid arthritis (RA) patients, lymphocytes accumulate in the synovial membrane and the synovial fluid. In the present study we have analyzed the expression of integrins and other adhesion molecules in synovial fluid lymphocytes (RA-SFL) and paired peripheral blood lymphocytes (RA-PBL) from 21 RA patients by immunofluorescence flow cytometry. We have also investigated the expression of these adhesion molecules on peripheral blood lymphocytes obtained from 13 sex- and age-matched healthy controls (CO-PBL). RA-SFL, which consisted mostly of T cells, showed higher expression of the integrin subunits beta 1 (CD29), VLA-1 alpha, -3 alpha, -4 alpha, -5 alpha and -6 alpha when compared to RA-PBL. In turn, RA-PBL showed lower expression of these molecules than CO-PBL. The expression of the immunoglobulin-related molecules CD2, CD54 (ICAM-1) and CD58 (LFA-3) was higher on RA-SFL when compared to RA-PBL or CO-PBL, and similar results were obtained with the beta 2 integrin subunits CD11a and CD18. In contrast, L-selectin (LECAM-1) and ICAM-2 were expressed at much lower levels on RA-SFL than on RA-PBL or CO-PBL. CD44, a receptor for hyaluronic acid and collagen, was expressed by most RA-SFL, RA-PBL and CO-PBL cells but at higher density on RA-SFL. The results indicate that RA-SFL express a distinct array of adhesion molecules, similar to the one of memory T lymphocytes. This characteristic phenotype may contribute to the lymphocytic infiltration of the synovium and to the pathogenesis of RA.

Adult↗

PubMed1992

Induction of intercellular adhesion molecule-1 (CD54) on isolated mouse pancreatic beta cells by inflammatory cytokines.

Insulin-dependent diabetes mellitus (IDDM) results from a T cell-dependent autoimmune destruction of insulin-producing pancreatic beta cells. In the present study, expression of adhesion molecule ICAM-1 (CD54) on pancreatic beta cells was studied in normal, obese hyperglycemic (ob/ob), and nonobese diabetic (NOD) mice. Freshly isolated pancreatic beta cells from ob/ob mice did not express ICAM-1, but treatment of the cells with IL-1-beta, TNF-alpha, or INF-gamma strongly induced its expression as measured by immunofluorescence flow cytometry. The cytokines acted in a dose- and time-dependent manner. Maximal induction by either cytokine occurred at 24 hr and thereafter expression decreased, except for INF-gamma. Immunoprecipitation from IL-1-beta-treated beta cells demonstrated a cell-surface glycoprotein with an apparent molecular weight of 95 kDa. ICAM-1 expression was undetectable on pancreatic beta cells of normal and ob/ob mice as measured by immunohistochemistry. In NOD mice at different ages (1 to 6 months) ICAM-1 was also undetectable on beta cells, in contrast to the strong expression on infiltrating mononuclear cells. The present study indicates that mouse pancreatic beta cells, under certain conditions, can express ICAM-1.

Animals↗

PubMed1992

Adhesion of activated T lymphocytes to vascular smooth muscle cells and dermal fibroblasts is mediated by beta 1- and beta 2-integrins.

Several studies during recent years have demonstrated the potential for vascular smooth muscle cells (SMC) and dermal fibroblasts to participate in immune interactions such as antigen presentation and alloreactivity. The molecular interactions mediating lymphocyte adhesion to these mesenchymal cells have, however, not previously been characterized in detail. In the present study we demonstrate ICAM-1 (CD54) expression by cultured human SMC and its up-regulation by IL-1, IFN-gamma, and bacterial lipopolysaccharide. Monoclonal antibodies were used to define the molecular interactions in the adhesion of 51Cr-labelled T lymphoblasts to adherent SMC and fibroblasts. ICAM-1 appeared to mediate adhesion of T lymphocytes by binding to the beta 2-integrin CD11a/CD18 (LFA-1) expressed by the lymphoblasts. We present evidence for the involvement of at least three different mechanisms in the adhesion of activated T lymphocytes to cultured fibroblasts. It was found that beta 2-integrin-mediated interaction could only account for less than half of the binding activity. The remaining adhesion was partly mediated by beta 1-integrins, presumably via VLA-5 since an anti-VLA-5 antibody and an RGD-containing peptide blocked adhesion to the same degree. However, antibodies to beta 1-, beta 2-, and beta 3-integrin subunits added together only inhibited adhesion by approximately 50%. The residual adhesion could be blocked by inhibition of cell metabolism and was increased by stimulation of the lymphocytes with phorbol ester, suggesting involvement of other, as yet undefined, adhesion molecules. The molecular interactions between lymphocytes and mesenchymal cells demonstrated in this study may have implications in several inflammatory conditions such as vasculitis, atherosclerosis, and connective tissue diseases.

Antigens, CD↗

PubMed1991

ICAM-2 peptides mediate lymphocyte adhesion by binding to CD11a/CD18 and CD49d/CD29 integrins.

Three fifteen-amino-acid polypeptides designated peptides 1, 2 and 3 were synthesised as likely candidates for mimicking the role of ICAM-2 as a ligand. The ability of each peptide to bind lymphoid cells was tested. Peptide 2 largely mediated cell attachment of unstimulated cells and this binding was only marginally increased by stimulating the cells with phorbol dibutyrate (P(Bu)2). Peptide 3 mediated minimal spontaneous cell attachment, but this binding was significantly enhanced following P(Bu)2 stimulation. Peptide 1 had no effect on cell attachment with or without stimulation. The cell attachment to peptide 2 was both temperature- and cation-dependent. Studies using specific monoclonal antibodies showed that with unstimulated cells, anti-VLA-4 alpha(CD49d) or beta chain (CD29) antibodies (KD4-13 and 4B4) and anti-CD18 (1B4) each partially inhibited the cell binding. Monoclonal antibodies against CD54 (ICAM-1; 84H10 or LB2), MHC class 1 (W6/32) and control mouse IgG had no effect. When anti-CD29 and anti-CD18 monoclonal antibodies were used concurrently, there was almost complete inhibition of the cell attachment. These observations indicated that cell adhesion via ICAM-2 is mediated: (i) predominantly by peptide 2 in unstimulated and P(Bu)2-stimulated cells, and also, to some extent, by peptide 3 in P(Bu)2-stimulated cells and (ii) by binding to both CD11/CD18 and CD49d/CD29 integrins.

Amino Acid Sequence↗

PubMed1991

A monoclonal antibody to the human leukocyte adhesion molecule intercellular adhesion molecule-2. Cellular distribution and molecular characterization of the antigen.

The DNA of the human leukocyte adhesion molecule intercellular adhesion molecule-2 (ICAM-2) was synthesized by the polymerase chain reaction, and a protein A-ICAM-2 fusion protein was expressed in Escherichia coli. The fusion protein was used as immunogen to obtain mAb to ICAM-2. The 6D5 antibody was selected by its reactivity in immunofluorescence with the endothelial cell line Eahy926. The antibody precipitated a 55,000 m.w. glycoprotein from radioactivity surface labeled cells and also reacted in Western blotting. As measured by immunofluorescence flow cytometry, the antibody reacted with lymphoblastoid B cells of normal origin, some Burkitt lymphoma cell lines, vascular endothelial cells, the endothelial cell line Eahy926, 4 and a subpopulation of Con A-stimulated blood mononuclear cells. The two Ig-like domains of ICAM-2 were separately expressed in E. coli, and the antibody was shown to react with the NH2-terminal domain. The antibody inhibited the CD11/CD18-dependent binding of HL-60 promyelocytic leukemia cells to transfected COS-1 cells.

Antibodies, Monoclonal↗