Expression of beta 1 integrins in human dental pulp in vivo: a comparative immunohistochemical study on healthy and chronic marginal periodontitis samples.

AIM: The objective of this study was to determine the tissue distribution of beta 1 integrin chains in sound human dental pulps and to compare the findings with connective tissue compartments of other organs and to pulp tissue in teeth extracted due to periodontal disease. METHODOLOGY: Freshly frozen pulp tissue samples from teeth extracted for orthodontic reasons were examined and compared to samples from teeth extracted due to chronic (marginal) periodontitis. beta 1 integrin chains were determined using an indirect-immunoperoxidase technique. Seven monoclonal antibodies recognizing alpha 1, alpha 2, alpha 3, alpha 4, alpha 5, alpha 6 and beta 1 chains of Very Late Activation Antigen (VLA) integrins were used for this purpose. RESULTS: VLA-1, VLA-2, VLA-3 and VLA-5 were expressed by vascular endothelium and vascular smooth muscle in varying intensities in both groups. VLA-6 reactivity was observed in the basal surfaces of arterial, venous and capillary endothelia. Our results indicate that there was no significant difference in the expression of VLA integrins in sound pulp tissue when compared to the samples from chronic (marginal) periodontitis and the connective tissue compartments of other viscera. CONCLUSION: The present findings suggest that human dental pulp tissue is not different from other connective tissue compartments in the body with respect to VLA integrin expression, and chronic marginal periodontitis does not affect pulp tissue to a histopathologically detectable extent.

Increase in expression of adhesion molecule receptors on T helper cells during antipsychotic treatment and relationship to blood-brain barrier permeability in schizophrenia.

OBJECTIVE: The authors estimated the expression of adhesion molecule receptors (VLA-4 and LFA-1) on T helper (CD4+) and T suppressor/cytotoxic (CD8+) lymphocytes in schizophrenic patients before and during antipsychotic treatment and studied the relationship of these subpopulations to CSF measures and blood-brain barrier permeability. METHOD: Blood was drawn from hospitalized patients with schizophrenia before (N = 45) and after (N = 22) neuroleptic treatment and from an age-matched comparison group (N = 41). Lumbar punctures were performed on 32 of the schizophrenic patients. RESULTS: During antipsychotic treatment there were significant increases in the percentage of VLA-4+/CD4+ and VLA-4+/CD8+ cells. VLA-4+/CD4+ and LFA-1+/CD4+ cells were both closely related to disturbance of the blood-brain barrier. Higher values for VLA-4+/CD4+ and LFA-1+/CD4+ cells were found in patients with a disturbed blood-brain barrier. CONCLUSIONS: The findings suggest that adhesion molecules are involved in immunoregulation between the central nervous system and the peripheral immune system in schizophrenia.

Tetraspanin CD9 is associated with very late-acting integrins in human vascular smooth muscle cells and modulates collagen matrix reorganization.

CD9, a member of the tetraspanin family, and very late-acting (VLA) integrins are known to associate and form functional units on the surface of several cell types. We studied the changes in expression of CD9 and beta1-integrins (CD29, VLA) in human vascular smooth muscle cells (VSMCs) under in vitro culture conditions mimicking proliferative vascular diseases. We also investigated possible interactions between CD9 and VLA integrins in VSMCs. We found that CD9 is highly expressed in VSMCs and is subject to modulation, depending on the proliferative/contractile state of the cells. In the contractile phenotype, the levels of CD9, CD81, another tetraspanin, and CD29 are approximately 50% of those found in the proliferative phenotype. Coimmunoprecipitation experiments showed physical association between CD9 and CD29. CD9 was mainly associated with alpha2 and alpha3-integrins (CD49b and c) and also with alpha5-integrin to a weaker extent. Functionally, the addition of anti-CD9 monoclonal antibodies (MoAbs) doubled the extent of collagen gel contraction mediated by VSMCs, a model for the reorganization of the extracellular collagen matrix occurring in the vessel wall. Anti-CD29 MoAbs inhibited gel contraction, but anti-CD9 MoAbs counteracted this inhibitory effect of anti-CD29 MoAbs. Transfection of human CD9 into Chinese hamster ovary cells more than doubled the extent of Chinese hamster ovary cell-mediated collagen gel contraction (130% stimulation), confirming a role for CD9 in extracellular matrix reorganization. Thus, CD9 seems to be involved in the modulation of VLA integrin-mediated collagen matrix reorganization by VSMCs. These findings suggest that high CD9 expression is associated with a proliferative state of VSMCs. The role of CD9 could be to modulate the function of VLA integrins on the surface of VSMCs.

Immunohistochemical and serological comparison of idiopathic and hepatitis C virus-associated forms of oral lichen planus.

The oral form of the inflammatory disease lichen planus occurs spontaneously due to unknown aetiological factors. However, it has recently been observed to occur with increased frequency in patients infected with the hepatitis C virus. Because of the prominent role of adhesion molecules in immune cell interactions, we have compared the expression of these antigens in the hepatitis C virus-associated and idiopathic forms of the disease. The results show similar patterns of expression of very late activation antigen-4, lymphocyte function-associated antigen-3 and intercellular adhesion molecule-1, but relatively elevated levels of these antigens in oral lichen planus patients with no hepatitis C virus infection. In addition to differences in Langerhans cell distribution, serum levels of "soluble" intercellular adhesion molecule-1 as well as immunoglobulin G were significantly increased in the hepatitis C virus-associated group. These findings show that there are some differences in the lesional and systemic immune reactivities of the two types of oral lichen planus which may be related to possibly distinct pathogenic mechanisms.

Expression of beta 1 integrins (very late antigens-4 and -5) on myeloma cells and clinical correlates in patients with multiple myeloma.

beta 1 Integrins are considered to be essential for the differentiation of bone-marrow B cells through an interaction with fibronectin-expressed bone-marrow stromal cells. The expression of very late antigens-4 (VLA-4) and -5 (VLA-5) by CD38bright bone-marrow cells in patients with multiple myeloma was measured by flow cytometry using specific monoclonal antibodies. The percentage of CD38bright bone-marrow cells appeared to correlated with that of bone-marrow plasma cells as judged by examination of bone-marrow smears (r = 0.911, P < 0.0001). Expression of VLA-4 and VLA-5 by CD38bright cells varied between patients, but the expression of VLA-4 was always equal to or greater than that of VLA-5. The ratio of VLA-4 to VLA-5 expression (VLA-4:VLA-5 ratio) was calculated and compared with the clinical features of the myeloma patients. A high VLA-4:VLA-5 ratio (> 2.0) was associated with the presence of plasmacytomas and urinary Bence-Jones protein was more common in this group. No other correlations between the clinical features of the disease and the expression of beta 1 integrins were found.

Depressed platelet status in an elderly patient with hemorrhagic stroke after thrombolysis for acute myocardial infarction. GUSTO-III Investigators.

BACKGROUND: Impaired platelet function has been reported in acute myocardial infarction (AMI) and stroke. However, prospective data on the changes of platelet status in patients before the occurrence of hemorrhagic stroke after thrombolytic therapy are unavailable. CASE DESCRIPTION: An 86-year-old male patient was among the 23 AMI patients enrolled in the platelet study for the GUSTO-III trial. He received 325 mg of aspirin daily for at least 6 years, suffered an AMI, and was successfully reperfused with alteplase, but after 44 hours developed a large hemorrhagic stroke resulting in paraplegia. Platelet aggregation and receptor expression were measured by flow cytometry and ELISA before thrombolysis and at 3, 6, 12, and 24 hours thereafter. The percentage of platelet aggregation was lower in the stroke patient at every time point when induced by 5 micromol/L of ADP, by 10 micromol/L of ADP, and by thrombin than in the rest of the AMI group. Ristocetin and collagen-induced aggregability were within the group range. Decreased platelet glycoprotein Ib, IIb, IIIa, and IIb/IIIa and vitronectin receptor expression were observed in the stroke patient. No other differences in p24 (CD9), very late antigen-2, P-selectin, and platelet/endothelial cell adhesion molecule-1 expression were determined. CONCLUSIONS: Profound depression of platelet status preceded the occurrence of hemorrhagic stroke in an elderly long-term aspirin user treated with thrombolytic therapy. Initial "exhausted" platelets may be responsible for the increased risk for hemorrhagic stroke after coronary thrombolysis.

Patterns of intermediate filaments, VLA integrins and HLA antigens in a new human biliary epithelial cell line sensitive to interferon-gamma.

BACKGROUND/AIMS: Intra-hepatic bile ducts are the primary site of damage in several immunologically mediated liver diseases. However, immunological processes underlying biliary epithelial cell recognition by T lymphocytes are poorly understood. Therefore, a convenient in vitro model that could mimic these immunologic disorders would be of great interest. METHODS: A human cell line (HuGB) was established from a metastasis of gallbladder adenocarcinoma in the liver. Intermediate filament expression was analysed by immunostaining, and gamma-glutamyl transpeptidase and albumin secretion were measured. VLA integrin expression pattern, expression of HLA class I and II antigens and ICAM-1 protein were analysed by flow cytometry and their modulation by interferon-gamma was quantitated using a QIFIKIT commercial kit. RESULTS: Histological analysis showed high similarity between the initial gallbladder adenocarcinoma and the established cell line. Cytokeratins 8 and 19 and vimentin showed strong positive staining in the established cell line. Gamma-glutamyl transpeptidase was secreted by these cells while albumin expression was negative. HuGB cells also expressed VLA-alpha2, VLA-alpha3, VLA-alpha6, VLA-beta1, but not VLA-alpha1, VLA-alpha4 and NCAM, a pattern of adhesion molecule expression compatible with the biliary epithelium. Also, similar to the biliary epithelium found in normal liver, HuGB cells expressed abundant HLA class I but few HLA class II antigens. We found that the expression of HLA antigens and ICAM-1 protein were increased during interferon-gamma treatment of HuGB cell line. CONCLUSIONS: Both phenotypic and morphological characteristics of HuGB cells suggested their biliary origin. Sensitivity of HuGB cells to interferon-gamma suggests that this new cell line could represent a suitable model to investigate the up-regulation of membrane antigens occurring in immune diseases involving biliary epithelial cells.

Histopathology of primary biliary cirrhosis with emphasis on expression of adhesion molecules.

In the initiation and progression of immune-mediated destruction of interlobular bile ducts and hepatocytes in primary biliary cirrhosis, T-cell-mediated responses to target antigen(s) expressed on the bile ducts and hepatocytes, as well as cellular adhesions via various adhesion molecules are critical. Intercellular adhesion molecule 1 and, to a lesser degree, vascular adhesion molecule 1 are increasingly expressed on the damaged bile ducts in primary biliary cirrhosis. In addition, lymphocyte function-associated antigens, very late antigens, endothelial-leukocyte adhesion molecule 1, and other adhesion molecules on the vascular endothelial cells and/or inflammatory cells, particularly activated lymphocytes, are also expressed in the portal tracts and hepatic parenchyma. These adhesion molecules are involved in the extravasation as well as epitheliotropic processes of inflammatory cells. Dendritic cells, particularly interdigitating ones in the periductal tissue, are positive for these immune molecules and also for the B-7 family. They may also be important in antigen presentation to CD4+ helper T cells and their activation. However, there is still controversy about whether the B-7 family is expressed on the bile ducts and, then, whether biliary epithelial cells work as an antigen presenting cell. Expression of a very late antigen family on the basolateral surface of bile ducts may be involved in the cell-cell and cell-matrix interactions. Soluble adhesion molecules may be involved in the regulation of immune-mediated bile duct lesions.

The expression of adhesion molecules in cigarette smoke-induced airways obstruction.

Cigarette smoking produces peripheral airway inflammation in all smokers, and chronic airways obstruction in approximately 20% of heavy smokers. The present study was designed to test the hypothesis that airways obstruction is related to changes in the expression of adhesion molecules involved in the recruitment of cells to sites of inflammation in the lung. Freshly resected lungs from heavy smokers with airways obstruction (n = 10) and from heavy smokers with normal lung function (n = 10) were collected in the operating room, inflated with optimal cutting temperature (OCT) medium and frozen over liquid nitrogen. Six micrometres thick cryostat sections cut from random samples of this tissue were stained, using immunohistochemistry, with monoclonal antibodies to the adhesion molecules on leucocytes: L-selectin, very late activation antigen-4 (VLA-4), CD11a/CD18, CD11b/CD18, CD11c/CD18; and on endothelial and epithelial surfaces: E-selectin, P-selectin, vascular cell adhesion molecule (VCAM-1), intercellular adhesion molecule (ICAM)-1 and ICAM-2 using the alkaline phosphatase anti-alkaline phosphatase (APAAP) technique. The slides were coded and the expression of each molecule scored by three observers using a semiquantitative grading system. Two inducible adhesion molecules, E-selectin on endothelium and CD11b on leucocytes, were also evaluated using quantitative morphometric analysis. The results showed a distribution of adhesion molecules that was consistent with the inflammatory response in the airways and parenchyma of all subjects but failed to show any differences between those with or without airways obstruction. We conclude that development of airways obstruction in heavy smokers cannot be explained by differences in the expression of adhesion molecules known to be involved in the control of cell traffic in the lung.

Changes in markers, receptors and adhesion molecules expressed on murine hemopoietic stem cells after a single injection of 5-fluorouracil.

Cytokines play a crucial role in the differentiation and proliferation of hemopoietic cells, and it has recently been found that adhesion molecules play crucial roles not only in differentiation and proliferation, but also in the homing and other functions of hemopoietic cells. We have very recently established a new method for purifying pluripotent hemopoietic stem cells (P-HSC) in mice by injecting 5-fluorouracil (5-FU). The P-HSC were found to be low-density, lineage marker-negative (Lin-), CD71- and major histocompatibility complex class I(high). In the present study, we analyze changes in the expression of various HSC markers (Sca-1 and CD34), receptors (c-kit and interleukin-6 receptor [IL-6R]) and adhesion molecules (very late activation antigen-4 [VLA-4], lymphocyte function-associated antigen-1 [LFA-1], and CD44) after 5-FU injection. The percentage of Sca-1+ cells increases after 5-FU treatment, reaching a maximum on day 3, whereas the percentage of IL-6R+ cells decreases, reaching a minimum on day 3. The percentage of CD34+ cells does not change after 5-FU treatment. The percentages of both c-kit(low) and c-kit(high) cells decrease, reaching a minimum on day 3 after 5-FU treatment, whereas the percentage of c-kit- cells reciprocally increases, reaching a maximum on day 3. However, there is no change in the expression of adhesion molecules (VLA-4, LFA-1 and CD44) on the P-HSC.

Expression of the adhesion molecules ICAM-1, VCAM-1, and E-selectin and their ligands VLA-4 and LFA-1 in chronic venous leg ulcers.

BACKGROUND: Leukocyte binding to endothelial cells (ECs) is thought to contribute to the pathogenesis of leg ulcers caused by chronic venous insufficiency. In other systems, such binding is mediated by the interaction of adhesion molecules such as intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule- (VCAM-1) and E-selectin (on ECs), and leukocyte function-associated antigen-1(LFA-1) and very late activated antigen-4 (VLA-4) (on Leukocytes). OBJECTIVE: Our purpose was to determine whether an increased expression of these adhesion molecules contributes to the pathogenesis of chronic venous insufficiency. METHODS: Twenty-seven biopsy specimens of inflamed dermatoliposclerotic skin adjacent to venous leg ulcers were stained immunohistochemically with monoclonal antibodies against ICAM-1, VCAM-1, LFA-1, VLA-4, and E-selectin. Staining intensity was compared with that of normal skin. RESULTS: Specimens of leg ulcers caused by chronic venous insufficiency showed increased expression of ICAM-1 and VCAM-1 but not of E-selectin on The expression of LFA-1 and VLA-4 on perivascular leukocytes was increased dramatically in comparison to healthy skin. CONCLUSION: Upregulation of ICAM-1 and VCAM-1 on ECs may contribute to the increased adherence and extravasation of LFA-1 and VLA-4-positive leukocytes in chronic venous insufficiency.

The expression of VLA integrins in the human thymus.

UNLABELLED: The integrin receptors are a family of transmembrane glycoproteins comprising non-covalent heterodimers. They interact with a wide variety of ligands including extracellular matrix glycoproteins, complement and other cells while their intracellular domains interact with the cytoskeleton. They participate in cell-matrix and cell-cell adhesion in many physiologically important processes including embryological development, hemostasis, thrombosis, wound healing, immune and nonimmune defense mechanisms, and oncogenic transformation. This investigation is focused on the histological distribution of the beta 1-integrins in the human thymus, using an indirect immunoperoxidase method. With the exception of VLA-4, none of the beta 1 integrins were expressed on thymocytes which were strongly positive in the cortex and perivascular compartment, somewhat weaker in the medulla. Thymic epithelial cells were positive for VLA-1, VLA-2, VLA-3 and VLA-6, but the distribution pattern of these molecules in epithelial cells at certain locations was quite different. VLA-1 was weakly expressed by both cortical and medullary epithelial cells. VLA-2 was strongly positive in cortical epithelial cells forming a dense framework at the peripheral cortex. VLA-3 and VLA-6 selectively stained a single flattened epithelial cell layer (perilobular epithelial cells) demarcating the peripheral cortex from the surrounding perivascular compartment. VLA-1,3,5,6 were also demonstrated in the endothelial cells and subendothelial layer of the thymic vasculature. IN CONCLUSION: the distribution of integrins in human thymus tissues is of special interest. Such distribution shows that the VLA integrins may have different functions in different areas. The data presented in this study may be important in evaluating the functional role of the VLA integrins in thymocyte maturation in different compartments of the thymus.

Immunohistochemical localization of very late activation integrins in healthy and diseased human gingiva.

The beta 1-integrins (VLA family) are cellular adhesion molecules (CAM) that play a major role in cell-cell and cell-matrix interactions. The expression pattern of CAM was studied in 5 clinically normal volunteers with healthy gingiva and in 18 patients with clinically different stages of periodontitis. In healthy human gingiva alpha 2, alpha 3 and alpha 6 integrin chains were found in a characteristic distribution, showing a broad continuous expression on the junctional and sulcular epithelium sites. The expression of these integrins was demonstrated primarily on the basal cell layers and in some cells of the stratum spinosum. Inflammatory stages of periodontitis revealed further upregulation of alpha 2, alpha 3 and alpha 6 integrins into the junctional and sulcular epithelial cells, which correlated with the stage of the periodontitis and the extent of the cellular infiltration. alpha 4 and alpha 6 were found to be the predominant beta 1 integrin chains on inflammatory cells. The amount of alpha 4 and alpha 6 positive infiltrative cells increased with the number of inflammatory cells. VCAM-1, the corresponding cell-cell ligand of VLA-4 (alpha 4) was present on the majority of subepithelial vessels in all stages of gingivitis and periodontitis. The alpha 5 subunit was expressed on both endothelium and gingival connective tissue cells. Samples from advanced periodontitis cases showed a higher number of alpha 5 positive mononuclear cells. In comparison to normal epidermis, human gingival epithelial cells express higher levels of integrins. This expression is further upregulated in advanced stages of periodontitis, indicating changes of the beta 1 integrin organization.

Low expression of adhesion molecules in a case of cutaneous T-cell lymphoma.

A case of cutaneous T-cell lymphoma (CTCL) with low expression of the adhesion molecules lymphocyte function-associated antigen-1 (LFA-1), intercellular adhesion molecule-1 (ICAM-1), and very late antigen-4 (VLA-4) is described. The patient was a 90-year-old man with red round homogeneous tumors on his scalp, trunk, and extremities. He had no history of definite erythema or plaque stage. A biopsy sample taken from a tumor revealed massive infiltration of atypical lymphocytes in the reticular dermis and subcutis with a definite clear zone. The atypical lymphocytes were medium-sized with slightly convoluted nuclei. Immunohistochemically, the infiltrates showed the phenotype of so-called memory T cells. On the basis of these features, the case was diagnosed as CTCL. Expression of LFA-1, ICAM-1 and VLA-4 on the infiltrates was 9%, 13% and 11%, respectively, which is much lower than that in classic mycosis fungoides. This finding suggests that loss of these adhesion molecules may contribute to loss of epidermotropism in the advanced stage of CTCL.

Expression of Fas/Apo-1 (CD95) and apoptosis in tumor cells from patients with plasma cell disorders.

Fas/Apo-1 antigen (CD95) is a cell surface molecule that directly mediates apoptosis. Fas expression was studied in five plasma cell lines, 11 multiple myeloma cases, and three plasma cell leukemia (PCL) cases. Induction of apoptosis by anti-Fas antibody was studied in five plasma cell lines and fresh plasma cells from eight patients. Apoptosis was confirmed by morphologic analysis alone or in combination with DNA electrophoresis analysis. Four of the five cell lines showed Fas expression, three of which showed induction of apoptosis by anti-Fas antibody. One cell line, RPMI 8226, showed the highest sensitivity for Fas-mediated apoptosis. High bcl-2 expression was found in KMS12PE, which showed resistance to Fas-mediated apoptosis despite its Fas expression. Plasma cells from seven fresh cases, including all five cases with high serum lactate dehydrogenase (LDH), showed expression of Fas antigen. Fas-induced apoptosis was found in five cases at various levels, although significant induction of apoptosis was found in only one case. Interestingly, Fas-independent apoptosis was induced during culture without anti-Fas antibody in cases with high serum LDH. These results indicate that plasma cells from aggressive myeloma with high LDH express Fas antigen and undergo apoptosis through either Fas-mediated or Fas-independent pathways. An understanding of the mechanism of apoptosis in malignant plasma cells should contribute to investigations of the pathophysiology of and therapy for myeloma/PCL.

[Association between expression of integrin (VLA-3, VLA-5) and malignancy in human colon-cancer].

The expression of the VLA-integrins beta 1, -2, -3, -5, -6 and alpha v beta 3 was studied immunohistochemically in the tissue sample from human colon-cancer. Furthermore, histological stage-grouping of the colon-cancer (I-V), additional vascular invasion such as lymphatic and blood-vessel invasion, was made to express the malignancy of the carcinoma, for making a comparison with the expression of the integrins. Immunohistologically, beta 1, VLA-2, and alpha v beta 3 were mildly expressed in the carcinoma cells and VLA-6, markedly expressed. These findings were not correlated with the malignant stage-grouping. For VLA-3, the carcinoma showed mild to marked expression with a diffuse distribution on the cell surface in the peripheral area of the carcinoma, nearly correlating with the histological stage of malignancy. While, the expression of VLA-5 was almost absent in the carcinoma. These results suggest that the enhanced expression of VLA-3 with suppressed expression of VLA-5 is functionally important for the carcinoma cell invasion and also for the metastasis.

[Comparison of the pattern of integrin expression between primary tumors and liver metastasis of gastric and colorectal cancers].

To investigate the interrelationship between integrin VLA3 overexpression and liver metastasis, immunohistochemical studies of VLA3 were made in 73 cases of gastric cancer (66 cases without liver metastasis, 7 cases with liver metastasis) and 15 cases of colorectal cancer (3 cases without liver metastasis, 12 cases with liver metastasis). The rate of integrin VLA3 expression in 69 primary gastric and colorectal cancers without liver metastasis was 41%, that was higher than that (0%) in the 19 primary tumors of gastric and colorectal cancers with liver metastasis. In contrast, the positive rate for integrin VLA3 staining in 19 cases involving liver metastasis of gastric and colorectal cancers was 58% (11/19), which was higher than that (0%) in primary tumors. These findings suggest that VLA3 may play an important role in the process of liver metastasis of gastric and colorectal cancers.

Human skin mast cells express functional beta 1 integrins that mediate adhesion to extracellular matrix proteins.

We have evaluated the adhesion of human cutaneous mast cells to several components of the extracellular matrix (plasma fibronectin, laminin, collagen type I and IV) and studied whether these cells express the beta 1 integrins potentially involved in the adhesion to these proteins. Human skin mast cells (5.1 +/- 1.5% pure) spontaneously adhered to fibronectin and laminin (0.1 to 10 micrograms/ml) immobilized on plastic surfaces (e.g., 14 +/- 7.2% and 14 +/- 4.4% adhesion at 10 micrograms/ml, respectively). Similar results were obtained with a 90% pure mast cell preparation. In contrast, cutaneous mast cells did not adhere to collagen type I (1.6 +/- 0.5% adhesion) or type IV (1.2 +/- 0.8% adhesion). Control adhesion in BSA-coated wells was < 5%. Mast cell adhesion to fibronectin was optimal after an incubation period of 60 to 90 min (t1/2 = 28.2 +/- 6.2 min), whereas adhesion to laminin was faster (t1/2 = 10.1 +/- 1.2 min), being nearly optimal after a 15-min incubation period. Human skin mast cell adhesion to fibronectin and laminin was found to be dependent on the presence of divalent cations in the extracellular medium. Dual-color immunofluorescence and flow cytometry were used to evaluate whether human skin mast cells (51.3 +/- 3.9% pure) express beta 1 integrins that may mediate cell adhesion to extracellular matrix proteins. These mast cells were found to express VLA (very late Ag)-3 (75.3 +/- 35.6 specific fluorescence intensity) and, to lesser degree, VLA-4 and VLA-5 receptors (8.0 +/- 2.5 and 6.9 +/- 3.2 specific fluorescence intensity, respectively). In contrast, VLA-1, VLA-2, and VLA-6 integrins were not expressed significantly. mAb to VLA-3, VLA-4, and VLA-5 each inhibited by 70% skin mast cell adhesion to fibronectin. mAb to VLA-3 nearly abolished mast cells adhesion to laminin, whereas anti-VLA-4 and anti-VLA-5 were ineffective. Finally, immunosuppressant cyclosporin A (100 nM) and FK-506 (10 nM) significantly inhibited mast cell adhesion to both fibronectin and laminin (p < 0.05). Our data demonstrate that human skin mast cells spontaneously adhere to fibronectin and laminin, and that this adhesion is mediated by VLA-3, VLA-4, and/or VLA-5 integrins on these cells. Interactions between these beta 1 integrins and extracellular matrix proteins may be involved in perivascular tissue localization of human mast cells in vivo.

Expression of cell adhesion molecules in inflammatory myopathies.

We examined the expression of cell adhesion molecules in 25 cases of inflammatory myopathies. Inflammatory myopathies showed upregulation of adhesion molecules. ICAM-1 was strongly expressed on endothelial cells as well as on fibroblasts and infiltrating leukocytes while the expression of VCAM-1, similar in its distribution, was much weaker. A few muscle fibers in polymyositis revealed sarcolemmal labeling for ICAM-1. ELAM-1 showed only weak expression on vessels. The inflammatory cellular infiltrates contained varying amounts of cells bearing the VCAM-1 ligand VLA-4 and the ELAM-1 ligand SLeX as well as large amounts of cells expressing LFA-1 alpha and beta, ligands of ICAM-1.

Systemic lupus erythematosus with necrotizing vasculitis and upregulated expression of VLA-4 antigen.

We report on a patient (S.A.), with well-defined SLE who developed a perforation of the ileum due to pathologically confirmed necrotizing vasculitis. No anti-DNA antibody was detected at the ileal perforation, and the serum complement level was normal. These findings raise the alternative possibility of a cell-mediated immune mechanism as a cause of necrotizing vasculitis. Upregulated expression and function of VLA-4 antigen on peripheral blood T cells were observed, suggesting that T cells with VLA-4 antigen may participate in the onset and/or perpetuation of vascular inflammation.