Immunosuppression by inhibition of cellular adhesion mediated by leukocyte function-associated antigen-1/intercellular adhesion molecule-1 in murine cardiac transplantation

BACKGROUND: Donor alloantigen-specific tolerance to vascularized allografts can be induced by several treatments, but the immunological mechanism(s) of these effects remain unclear. One hypothesis is that allograft unresponsiveness is correlated with a shift in the pattern of expression of the T helper 1 versus T helper 2 T-cell cytokines. We report here an extensive analysis of murine cardiac allografts, during normal first set rejection and in mice treated with anti-adhesion molecule monoclonal antibodies (mAbs), a regimen that results in prolonged unresponsiveness. METHODS: A combination of immunohistochemical staining with a panel of mAbs, and in situ hybridization with a panel of digoxigenin-labeled riboprobes, was performed on frozen-tissue sections of cardiac allografts. RESULTS: In several strain combinations, injection of anti-leukocyte function-associated antigen-1 and anti-intercellular adhesion molecule-1, from day 0 to day 6 after transplantation, results in significant long-term survival. Examination of tolerated cardiac allografts by in situ hybridization and immunohistochemical staining shows an altered cytokine expression pattern, although the frequency of CD3 and CD4 cells is not dramatically reduced. These allografts show a decreased frequency of interferon-gamma and interleukin (IL)-2-expressing cells and a slightly increased frequency of cells expressing IL-4 and IL-10, compared with unmodified acute rejection. A direct role of these changes in T-cell cytokine expression is demonstrated by reversal of tolerance induction and rejection of the allograft by in vivo injection of either anti-IL-10 or anti-IL-4 mAb. CONCLUSIONS: Although there are significant differences in the frequency of different cellular subsets and patterns of cytokine gene expression, these differences are quantitatively subtle, suggesting a delicately balanced immune response that can develop a pattern of specific unresponsiveness, with relatively minor alterations in the specific T-cell response.     

淋巴细胞功能相关抗原-1/细胞间黏附分子-1介导的细胞因子诱导的杀伤细胞体外抑瘤机制

目的 探讨淋巴细胞功能相关抗原-1(LFA-1)/细胞间黏附分子-1(ICAM-1)介导的细胞因子诱导杀伤细胞(CIK)的体外抑瘤机制.方法 从白血病患儿外周血分离淋巴细胞,经过干扰素-γ(IFN-γ)、抗CD3单克隆抗体(CD3McAb)、白细胞介素-2(IL-2)诱导并与树突状细胞(DC)共培养,获得大量的DC-CIK.在经10、20μg/ml等不同质量浓度小鼠抗人LFA-1单克隆抗体处理后,采用MTT法研究DC-CIK细胞对多种白血病细胞株的杀伤活性,RT-PCR与Western blotting方法检测GATA-3和T-bet基因表达水平的变化.ELISA方法测定DC-CIK细胞释放细胞因子IL-12、IFN-γ、肿瘤坏死因子-α(TNF-α)的表达水平.结果 诱导后的DC-CIK细胞形态规则,经不同浓度的LFA-1单克隆抗体处理后,MTT结果:20μg/ml LFA-1单克隆抗体封闭组DC-CIK细胞对B95细胞杀伤作用下降最为明显(t=10.138,P＜0.05);RT-PCR与Western blotting结果:20μg/ml LFA-1单克隆抗体封闭的B95细胞组,GATA-3基因mRNA水平和蛋白水平表达增加最为明显(t=16.386,P＜0.05;t=22.652,P＜0.05);同时T-bet基因mRNA水平和蛋白水平表达降低最为明显(t=17.728,P＜0.05;t=17.452,P＜0.05);ELISA结果:20μg/ml LFA-1单克隆抗体封闭的B95细胞组中细胞因子IL-12、IFN-γ、TNF-α分泌水平下降最为明显(t=21.621,P＜0.05;t=13.739,P＜0.05;t=15.278,P＜0.05).结论 GATA-3和T-bet基因参与了LFA-1/ICAM-1介导的DC-CIK抑瘤途径,并且通过分泌Th1型细胞因子IL-12、IFN-γ、TNF-α等发挥抑瘤作用.     

Accessory cell function of keratinocytes for superantigens. Dependence on lymphocyte function-associated antigen-1/intercellular adhesion molecule-1 interaction

A growing body of evidence points to a role for epidermal keratinocytes as active participants in immunologic reactions. Inasmuch as certain T cell-mediated skin diseases, such as psoriasis and atopic dermatitis, are triggered by microbial infection, we asked whether multipassaged human keratinocytes could provide the costimulatory signals necessary to induce autologous T cell proliferation in response to bacterial-derived super-antigens. On exposure to IFN-gamma, keratinocytes are induced to express HLA-DR and HLA-DQ class II MHC Ag, and the lymphocyte function-associated Ag-1 counter-receptor intercellular adhesion molecule-1 (ICAM-1). This change in keratinocyte phenotype is accompanied by the ability of these cells to support T cell proliferation induced by two different bacterial-derived superantigens, staphylococcal enterotoxins A and B. Superantigen-driven proliferation in the presence of IFN-gamma-treated keratinocytes was significantly inhibited (70-90% reduction) by mAb against the LFA-1 alpha- or beta-chain or ICAM-1. Proliferation was not inhibited by mAb against the CD28 ligands BB-1 or B7, even though these keratinocytes express BB-1. In addition to previous defined roles for class II MHC Ag, stimulation of LFA-1 on the T cells by ICAM-1 on the keratinocytes also plays an important costimulatory role in this superantigen-mediated response. The accessory cell capability of keratinocytes was not unique to superantigen driven responses as PHA, as well as anti-CD3 mAb also induced vigorous T cell proliferation when IFN-gamma-treated keratinocytes were added. However, IFN-gamma-treated keratinocytes consistently failed to provoke an allogeneic response. These data demonstrate that 1) keratinocytes can serve as accessory cells for T cell proliferation using a variety of different stimuli, 2) the LFA-1/ICAM-1 interaction plays a major role in keratinocyte-mediated costimulation, and 3) previous reports in which IFN-gamma-treated keratinocytes failed to support T cell proliferation to nominal or alloantigens, may reflect impaired Ag presentation via class II MHC molecules, rather than lack of necessary costimulatory signals. These findings highlighting the accessory cell function of keratinocytes may have implications for our understanding of the pathogenesis of immunologic disorders of the skin.     

Involvement of lymphocyte function-associated antigen-1 and intercellular adhesion molecule-1 in osteoclastogenesis: a possible role in direct interaction between osteoclast precursors

In our search for molecules involved in the process of osteoclast differentiation, we examined the surface phenotypes of the preosteoclast-like cells and osteoclast-like multinucleated cells (MNCs) formed in bone marrow cultures, using monoclonal antibodies recognizing different antigen molecules expressed on hematopoietic cells. Among these cell surface antigens, lymphocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) were highly expressed on mononuclear cells in the cultures for forming preosteoclast-like mononuclear cells. The double detection of these two antigen molecules with osteoclast-specific antigen and with calcitonin receptor, using a fluorescence-activated cell sorter or autoradiography technique, revealed that LFA-1 and ICAM-1 were expressed on the preosteoclasts. The expression of ICAM-1 was detected on both preosteoclasts and osteoclast-like MNCs, whereas the expression of LFA-1 was restricted to preosteoclasts. We designed a peptide with the sequence of the binding site of ICAM-1 against the ligand LFA-1. In the whole bone marrow culture system for forming osteoclast-like MNCs, a significant inhibition of MNC formation was observed by the addition of this peptide. These results strongly suggest the involvement of an LFA-1/ICAM-1-interaction in osteoclastogenesis.     

Soluble forms of intercellular adhesion molecule-1 inhibit insulitis and onset of autoimmune diabetes

Increased concentration of circulating adhesion molecules in human serum have been described in different immune-mediated diseases. Recently, we proposed an immunomodulatory function of soluble forms of the intercellular adhesion molecule-1 (ICAM-1) during the pathogenesis of human Type I (insulin-dependent) diabetes mellitus. To test this hypothesis in nonobese diabetic (NOD) mice, a spontaneous animal model for human Type I diabetes, two recombinant forms of soluble murine ICAM-1 were generated, one monomeric soluble ICAM-1 containing all five extracellular Ig-like domains of ICAM-1 (rICAM-1) and one dimeric protein with the N-terminal extracellular domains fused to the constant regions of murine IgG2a (rICAM-1-Ig). Beginning at age 35 days prediabetic NOD mice received i. p. injections of 5 microg recombinant ICAM-1-proteins three times a week for 4.5 months. At day 170 diabetes development was reduced (p < 0.001) in NOD mice receiving rICAM-1 (8%) or rICAM-1-Ig (8%) treatment in comparison with sham treated animals (45%). After termination of therapy animals treated with multimeric rICAM-1-Ig were protected longer than animals treated with rICAM-1. Prevention of diabetes was associated with decreased infiltration of pancreatic islets by mononuclear cells. A selective downregulation of Th1-type cytokine expression was observed in a second set of experiments in which diabetes development was synchronised by cyclophosphamide. These data support the hypothesis that circulating forms of adhesion molecules have an immunomodulatory function and can intervene in islet inflammation.     

Leukocyte integrin very late antigen-4/vascular cell adhesion molecule-1 adhesion pathway in splanchnic artery occlusion shock

Two MAIPA (monoclonal antibody [MAb] immobilization of platelet antigen) assays were performed to determine (a) autoantibodies to platelet glycoproteins (GP) and (b) serum antibodies recognizing mouse MAbs used in the assay. In MAIPA I, control platelets were incubated simultaneously with human serum and a mouse MAb to a platelet glycoprotein (GP IIb-IIIa, Ib-IX, Ia-IIa, IV and p24). In MAIPA II, the control platelets were incubated first with the human serum and then, after washing, with the selected mouse MAb. A series of 25 patients with autoimmune thrombocytopenic purpura (ATP) associated or not with other autoimmune states were examined. Autoantibodies (both MAIPA I and MAIPA II positive) or anti-mouse Abs (MAIPA I positive and MAIPA II negative) were frequent in both groups of patients. Statistically significant differences existed in the incidence of anti-mouse Abs between patients (56.5%) and healthy donors (10%). This suggests that their production may be related to thrombocytopenias associated with autoimmune disease. We speculate that the presence of anti-mouse antibodies could reflect an abnormality in the immunological modulation of the idiotypic network.     

Identification of the binding site in intercellular adhesion molecule 1 for its receptor, leukocyte function-associated antigen 1

Intercellular adhesion molecule 1 (ICAM-1, CD54) is a member of the Ig superfamily and is a counterreceptor for the beta 2 integrins: lymphocyte function-associated antigen 1 (LFA-1, CD11a/CD18), complement receptor 1 (MAC-1, CD11b/CD18), and p150,95 (CD11c/CD18). Binding of ICAM-1 to these receptors mediates leukocyte-adhesive functions in immune and inflammatory responses. In this report, we describe a cell-free assay using purified recombinant extracellular domains of LFA-1 and a dimeric immunoadhesin of ICAM-1. The binding of recombinant secreted LFA-1 to ICAM-1 is divalent cation dependent (Mg2+ and Mn2+ promote binding) and sensitive to inhibition by antibodies that block LFA-1-mediated cell adhesion, indicating that its conformation mimics that of LFA-1 on activated lymphocytes. We describe six novel anti-ICAM-1 monoclonal antibodies, two of which are function blocking. Thirty-five point mutants of the ICAM-1 immunoadhesin were generated and residues important for binding of monoclonal antibodies and purified LFA-1 were identified. Nineteen of these mutants bind recombinant LFA-1 equivalently to wild type. Sixteen mutants show a 66-2500-fold decrease in LFA-1 binding yet, with few exceptions, retain binding to the monoclonal antibodies. These mutants, along with modeling studies, define the LFA-1 binding site on ICAM-1 as residues E34, K39, M64, Y66, N68, and Q73, that are predicted to lie on the CDFG beta-sheet of the Ig fold. The mutant G32A also abrogates binding to LFA-1 while retaining binding to all of the antibodies, possibly indicating a direct interaction of this residue with LFA-1. These data have allowed the generation of a highly refined model of the LFA-1 binding site of ICAM-1.     

Molecular comparison of soluble intercellular adhesion molecule (sICAM)-1 and sICAM-3 binding to lymphocyte function-associated antigen-1

The interactions of intercellular adhesion molecules-1 and -3 (ICAM-1 and ICAM-3) with lymphocyte function-associated antigen-1 (LFA-1) have been characterized and compared on the molecular and cellular level. Enzyme-linked immunosorbent-based molecular assays have been utilized to calculate the binding affinities of soluble ICAM-1 (sICAM-1) and soluble ICAM-3 (sICAM-3) for LFA-1. Consistent with previously published data, we found that sICAM-1 binds to LFA-1 with an affinity of approximately 60 nM. In contrast, sICAM-3 binds to LFA-1 with an affinity approximately 9 times weaker ( approximately 550 nM). Both sICAM-1 and sICAM-3 require divalent cations for binding. Specifically, both Mg2+ and Mn2+ support high affinity adhesion, although interestingly, high concentrations of Ca2+ decrease the affinity of each molecule for LFA-1 substantially. Furthermore, a panel of anti-LFA-1 monoclonal antibodies were characterized for their ability to block sICAM-1 and sICAM-3/LFA-1 interactions in molecular and cellular assays to help distinguish binding sites on LFA-1 for both molecules. Finally, molecular and cellular competition experiments demonstrate that sICAM-1 and sICAM-3 compete with each other for binding to LFA-1. The above data demonstrate that sICAM-1 and sICAM-3 share a common binding site or an overlapping binding site on LFA-1 and that the apparent differences in binding sites can be attributed to different affinities of sICAM-1 and sICAM-3 for LFA-1.     

Molecular regulation of the interaction between leukocyte function-associated antigen-1 and soluble ICAM-1 by divalent metal cations

Surface plasmon resonance (SPR) was used to investigate and characterize the interaction between LFA-1 and sICAM-1 (a soluble form of ICAM-1). Full-length LFA-1 was immobilized on a hydrophobic surface, and sICAM-1 binding was monitored in a flow cell format. The binding of sICAM-1 to LFA-1 was specific and dependent upon Mg2+; Abs to both sICAM-1 and LFA-1 blocked the interaction, and EDTA abolished all binding. Association and dissociation rate constants (k(a) and k(d), respectively) for sICAM-1 were 2.24 x 10(5) M(-1) s(-1) and 2.98 x 10(-2) s(-1), respectively, giving a calculated K(ICAM) of 133 nM. Since the LFA-1/ICAM-1 interaction is highly sensitive to the presence of metal cations, SPR was also used to probe the affinity of the metal binding sites. The K(Mg) values were 160 and 12 microM in the absence (EGTA) and the presence of Ca2+ (100 microM), respectively; in addition, K(Mn) was 2 microM in the presence of Ca2+ (100 microM). Increasing Ca2+ into the millimolar concentration range, however, resulted in a competitive displacement of Mg2+/Mn2+ and decreased sICAM-1 binding. Based on these data, a synergistic model for the molecular regulation of LFA-1 by divalent metal cations is proposed, and implications to cellular adhesion are discussed.     

Activation of peripheral blood T cells by interaction and migration through endothelium: role of lymphocyte function antigen-1/intercellular adhesion molecule-1 and interleukin-15

Cell adhesion molecules have a key role in the migration of T cells to inflammatory foci. However, the effect of the endothelial-lymphocyte interaction on the activation of the latter cells remains unresolved. We have studied the effect of resting and stimulated endothelial cells (ECs) on the activation of peripheral blood T cells (PBTLs), as assessed by the expression of CD69 and CD25 activation antigens. The incubation of PBTLs with tumor necrosis factor-alpha-activated EC monolayers, either alive or fixed, induced the expression of CD69 but not CD25, preferentially in the CD8(+) CD45RO+ cell subset. Furthermore, it induced the production of cytokines such as IFN-gamma, but not that of interleukin-2 (IL-2) and IL-4. EC treated with other stimuli such as IL-1beta, IFN-gamma, or lipopolysaccharide also showed the same proactivatory effect on T cells. Lymphocyte activation was almost completely inhibited by blocking anti-CD18 and anti-intercellular adhesion molecule-1 (anti-ICAM-1) monoclonal antibodies (MoAbs), but only slightly affected by MoAbs against CD49d, vascular cell adhesion molecule-1, and anti-IL-15. In addition, the interaction of PBTL with immobilized ICAM-1 induced CD69 expression in the same memory T-cell subset. IL-15 induced T-cell activation with expression of CD69 and CD25, and production of IFN-gamma, and its effect was additive with that triggered by cell adhesion to either EC or immobilized ICAM-1. The transmigration of PBTLs through either confluent EC monolayers or ICAM-1-coated membranes also induced efficiently the expression of CD69. When IL-15 was used as chemoattractant in these assays, a further enhancement in CD69 expression was observed in migrated cells. Together these results indicate that stimulated endothelium may have an important role in T-cell activation, through the lymphocyte function antigen-1/ICAM-1 pathway, and that IL-15 efficiently cooperates in this phenomenon. These observations could account for the abundance of CD69(+) cells in the lymphocytic infiltrates of several chronic inflammatory diseases.     

Dominant-negative effect of the lymphocyte function-associated antigen-1 beta (CD18) cytoplasmic domain on leukocyte adhesion to ICAM-1 and fibronectin

The cytoplasmic domains of LFA-1 (CD11a/CD18) are thought to play an important role in the regulation of LFA-1 function. To further elucidate the role of the LFA-1 cytoplasmic domains, we transfected chimeric proteins consisting of the extracellular domain of CD4 fused with the transmembrane and cytoplasmic domains of LFA-1 into T and B cell lines, EL-4 and A20, respectively, and examined their effects on LFA-1-mediated cell adhesion. The CD4/18, but not CD4/11a, chimera profoundly inhibited LFA-1-mediated cell adhesion to ICAM-1, as well as cell spreading following cell adhesion. Unexpectedly, cell adhesion to fibronectin was also inhibited by the CD4/18 chimera. The CD4/18 chimera did not affect the expression of endogenous LFA-1 or the association of CD11a and CD18. Truncation of the carboxyl-terminal 13 amino acid residues of the CD18 cytoplasmic domain of the chimera completely abrogated the inhibitory effect on LFA-1. Among these amino acid residues, the carboxyl-terminal six residues were dispensable for the inhibitory effect in EL-4 cells, whereas it significantly reduced the inhibitory activity of CD4/18 in A20 cells. A larger truncation of the CD18 cytoplasmic domain was needed to fully abrogate the inhibitory effects of CD4/18 on the adhesion to fibronectin. These results show that 1) the CD4/18 chimera has dominant-negative effects on cell adhesion mediated by LFA-1 as well as fibronectin receptors, and 2) amino acid residues of the CD18 cytoplasmic domain involved in the inhibition of LFA-1 seem to be different from those for fibronectin receptors.     

Expression of intercellular adhesion molecule-1 in mice with Pseudomonas-induced pyelonephritis

PURPOSE: To investigate the role of intercellular adhesion molecule-1 (ICAM-1) in the renal inflammatory process, we studied the time-course fluctuation of ICAM-1 expression on inflammatory lesions in mice with experimentally induced bacterial pyelonephritis and the effect of in vivo administration of an anti-ICAM-1 monoclonal antibody (mAb) on leukocytic migration. MATERIALS AND METHODS: Ascending pyelonephritis was induced by transurethral instillation of Pseudomonas aeruginosa, and the expression of ICAM-1 in the pyelonephritic lesions was studied by immunohistochemical methods. RESULTS: The expression of ICAM-1 on the pyelonephritic lesions closely paralleled the degree of infiltration of neutrophils and macrophages until 3 days after infection. At 7 days after infection, though the degree of infiltration of these cells was quite high, expression of ICAM-1 was reduced. Treatment with the anti-ICAM-1 mAb in mice with bacterial pyelonephritis resulted in suppression of influx of neutrophils and macrophages in the infected sites until 3 days after infection. However, at 7 days after infection inhibition of the influx of these cells was not seen. CONCLUSIONS: These results suggest that ICAM-1 expression is transient and plays a key role in the influx of neutrophils and macrophages associated with the early-phase response, and that in the late phase ICAM-1 independent adhesion molecules may be more predominant.     

Constitutive chemokine production results in activation of leukocyte function-associated antigen-1 on adult T-cell leukemia cells

Adult T-cell leukemia (ATL) is characterized by massive infiltration of circulating ATL cells into a variety of tissues, a finding often associated with poor prognosis. Leukocyte migration from circulation into tissue depends on integrin-mediated adhesion to endothelium, and integrins are tightly regulated by several stimuli, such as inflammatory chemokines. However, the exact mechanisms that enhance adherence of leukemic cells to the endothelium and infiltration into tissues remain to be fully understood. We investigated the mechanisms of extravasation of leukemic cells using ATL cells and report the following novel features of endogenous chemokine-induced adhesion of ATL cells to the endothelium. ATL cells spontaneously adhered to endothelial cells without exogenous stimulation. Integrin leukocyte function-associated antigen-1 (LFA-1) on ATL cells was spontaneously activated. ATL cells produced high amounts of chemokines, macrophage inflammatory protein-1alpha (MIP-1alpha), and MIP-1beta. Adhesion of ATL cells to endothelial cells and the expression of activated form of LFA-1 were reduced by pretreatment with pertussis toxin, wortmannin, or anti-MIP-1alpha and MIP-1beta antibodies or transfection with antisense of MIP-1alpha or MIP-1beta. Spontaneous polymerization of cytoskeletal F-actin was observed in ATL cells, which was also inhibited by pertussis toxin and wortmannin. We propose that ATL cells adhere to endothelial cells through an adhesion cascade similar to normal leukocytes and that the chemokines produced by ATL cells are involved in triggering integrin LFA-1 through cytoskeletal rearrangement induced by G-protein-dependent activation of phosphoinositide 3-kinases in an autocrine manner. These events result in a strong adhesion of ATL cells to the endothelium and spontaneous transendothelial migration.     

Expression of membrane and soluble intercellular adhesion molecule-1 in Graves'' disease

Understanding the epidemiology of equine colic is directly relevant to the management of individual horses with colic. In this article, the epidemiology of colic is reviewed with emphasis on epidemiologic studies that have identified specific factors associated with increased risk of colic and epidemiologic studies that are designed to predict the need for surgery and prognosis in horses with colic. Despite the magnitude of the problem of equine colic, much remains to be learned about the epidemiology of this disease.     

Assessment of the role of leucocyte function-associated antigen-1 in homotypic adhesion of activated B lymphocytes

In this study we investigated how T-cell-dependent stimuli, via interleukin-4 (IL-4) or CD40 ligation, influence homotypic B-cell adhesion when compared with induction by the T-cell-independent stimulus lipopolysaccharide (LPS). Using primary murine B cells, we found that T-cell-dependent stimulation led to increased aggregation as compared to that induced by LPS. The adhesion was to a large extent dependent on the adhesion molecule, lymphocyte function-associated antigen-1 (LFA-1). We found that activation of B cells with the mitogenic stimuli induced an increased avidity of LFA-1 for its ligand, intercellular adhesion molecule-1 (ICAM-1). The increase was stable and different from that induced by phorbol esters. Although adhesion was reduced using B cells from LFA-1(-/-) mice, aggregation occurred in response to T-cell-dependent stimuli. Our data suggest that adhesion of B lymphocytes is regulated in different modes. One is induced by antigen and leads to a transient conformational change of the LFA-1 molecule. Another is induced by mitogenic stimuli and leads to stable avidity increase of LFA-1, possibly via activation of cytoskeletal anchorage. A third is LFA-1 independent, of low avidity and is induced by T-cell-dependent stimuli.     

新生儿败血症血清降钙素原和可溶性细胞间黏附分子-1的变化

目的 观察新生儿败血症患儿血清降钙素原(PCT)和可溶性细胞间黏附分子-1(sICAM-1)的变化.方法 新生儿败血症患儿56例,其中30例患儿血培养阳性(病原确诊组),26例血培养阴性(临床诊断组),取同期出生的新生儿25名作为对照组,分别应用化学发光法和酶联免疫吸附法测定患儿血清PCT和sICAM-1水平,同时进行新生儿危重评分.结果 败血症组血清sICAM-1和PCT明显高于对照组,且病原确诊组的血清PCT和sICAM-1水平又明显高于临床诊断组,差异均有统计学意义(P＜0.01).血清sICAM-1和PCT水平与新生儿危重评分呈负相关(γ=-0.778,P＜0.01;γ=-0.851,P＜0.01).结论 PCT和sICAM-1可作为新生儿败血症早期诊断的敏感指标.