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Biomedical subjects

T J Lawley

Publications and source records attributed to T J Lawley.

At least 19 recordsLinked to original sources
PubMed1992

Regulation of vascular cell adhesion molecule 1 on human dermal microvascular endothelial cells.

Vascular endothelial cell adhesion molecule 1 (VCAM-1) is an adherence molecule that is induced on endothelial cells by cytokine stimulation and can mediate binding of lymphocytes or tumor cells to endothelium. Because these interactions often occur at the level of the microvasculature, we have examined the regulation of expression of VCAM-1 in human dermal microvascular endothelial cells (HDMEC) and compared it to the regulation of VCAM-1 in large vessel human umbilical vein endothelial cells (HUVEC). Both cell populations were judged pure as assessed by expression of von Willebrand factor and uptake of acetylated low density lipoprotein. Expression of VCAM-1 was not detectable on either unstimulated HDMEC or HUVEC when assessed by ELISA or flow cytometry. Stimulation of either HDMEC or HUVEC with TNF-alpha resulted in a time- and dose-dependent induction of VCAM-1. However, although TNF-alpha-induced cell surface and mRNA expression of VCAM-1 in HDMEC was transient, peaking after 16 h of stimulation, TNF stimulation led to persistently elevated cell surface expression of VCAM-1 on HUVEC. IL-1 alpha also induced cell surface expression of VCAM-1 on HUVEC in a time- and dose-dependent manner, but stimulation of HDMEC with IL-1 alpha at doses up to 1000 U/ml failed to induce significant cell surface expression. However, IL-1 alpha induced time- and dose-dependent increases in ICAM-1 on HDMEC. Similarly, IL-4 induced VCAM-1 expression and augmented TNF-alpha-induced expression on HUVEC but did not affect VCAM-1 expression on HDMEC. Binding of Ramos cells to cytokine-stimulated endothelial cell monolayers correlated with VCAM-1 induction. Increased binding was seen after stimulation of HDMEC with TNF-alpha, which was blocked by anti-VCAM-1 mAb, but no increases in binding were noted after stimulation of HDMEC monolayers with IL-1 alpha. These data provide additional evidence for the existence of endothelial cell heterogeneity and differences in cell adhesion molecule regulation on endothelial cells derived from different vascular beds.

Cell Adhesion Molecules↗
PubMed1992

Human dermal microvascular endothelial but not human umbilical vein endothelial cells express CD36 in vivo and in vitro.

CD36 is an 88-kDa glycoprotein that has been identified on platelets, monocytes, and some endothelial cells. Experimental evidence suggests that CD36 mediates the binding of Plasmodium falciparum-infected RBC to a variety of cells, and therefore may play a role in the vascular complications associated with malaria. Additionally, CD36 may also bind the extracellular matrix proteins thrombospondin and collagen. Human umbilical vein endothelial cells have been used in in vitro models examining the binding of P. falciparum RBC to endothelial cells, but they do not consistently express cell surface CD36. Inasmuch as human dermal microvascular endothelial cells (HDMEC) differ in a variety of ways from large vessel endothelial cells, we have examined HDMEC for cell surface expression of CD36 in vivo and in vitro. Direct immunofluorescence of skin showed bright staining of HDMEC with antibody recognizing CD36 and flow cytometric analysis of cultured HDMEC revealed cell surface expression. In contrast, large vessel endothelial cells were not stained with antibody recognizing CD36 in vivo and cultured cells derived from umbilical vein failed to express cell surface CD36 in vitro. Western immunoblots of lysates of HDMEC but not human umbilical vein endothelial cells demonstrated an 88-kDa protein that comigrated with CD36 from platelets. Functional studies demonstrated that adherence of PRBC to HDMEC was inhibited up to 66% by mAb recognizing CD36. Furthermore, the expression of CD36 on HDMEC was increased in a dose- and time-dependent manner by IFN-gamma, and was decreased by protein kinase C agonists. These data demonstrate that HDMEC express functionally active CD36 and this expression can be positively and negatively regulated by soluble factors. This study demonstrates that HDMEC are useful in the study of CD36-mediated binding of PRBC to endothelial cells in vitro and provides further evidence of distinct phenotypic differences between HDMEC and large vessel endothelial cells.

Antigens, CD↗
PubMed1992

VCAM-1-, ELAM-1-, and ICAM-1-independent adhesion of melanoma cells to cultured human dermal microvascular endothelial cells.

We have examined the mechanisms by which tumor cells bind to endothelial cells utilizing cultured melanoma cells and microvascular endothelial cells derived from human dermis (HDMEC). The ability of biologic response modifiers (BRM) to modulate the adhesion of melanoma cells to HDMEC was defined and those results were compared with results from human umbilical vein endothelial cells (HUVEC). SK-MEL-2, WM266-4, and Hs 294T melanoma cells all bound to HDMEC and HUVEC monolayers and adherence of melanoma cells was enhanced in a dose- and time-dependent manner by the treatment of HDMEC with interleukin 1 (IL-1) alpha or tumor necrosis factor (TNF) alpha. Similar increases in binding to HDMEC or HUVEC were induced after BRM stimulation, although baseline melanoma cell binding to HUVEC tended to be slightly higher than to HDMEC. In contrast, whereas phorbol 12-myristate 13-acetate (PMA) augmented melanoma cell adherence to HDMEC, PMA failed to increase adherence to HUVEC. The alterations in melanoma cell binding were induced only after pretreatment of endothelial and not melanoma cells with PMA. Studies of the expression of cell adhesion molecules (CAM) on HDMEC and HUVEC using enzyme-linked immunosorbent assay showed that vascular cell adhesion molecule 1 (VCAM-1) is not induced by PMA on HDMEC and intercellular adhesion molecule 1 (ICAM-1) is downregulated on HDMEC by PMA treatment. Endothelial leukocyte adhesion molecule 1 (ELAM-1) is induced by PMA, IL-1 alpha, or TNFalpha, but its expression does not correlate with increased melanoma cell binding MoAb recognizing VCAM-1-inhibited TNFalpha-induced increases in melanoma cell binding to HUVEC. However, anti-VCAM-1 antibody failed to clock melanoma cell binding to PMA or IL-1 alpha-stimulated HDMEC and only partially inhibited melanoma cell binding to TNF alpha-stimulated HDMEC. This study demonstrates that PMA and IL-1 alpha-induced increases in melanoma cell adherence to HDMEC are not mediated via known CAM, including ICAM-1, VCAM-1, or ELAM-1, and may be affected through microvessel-specific novel proteins not previously described on endothelial cells.

Antibodies, Monoclonal↗
PubMed1992

HMEC-1: establishment of an immortalized human microvascular endothelial cell line.

The study of human microvascular endothelial cells has been limited, because these cells are difficult to isolate in pure culture, are fastidious in their in vitro growth requirements, and have a very limited lifespan. In order to overcome these difficulties, we have transfected human dermal microvascular endothelial cells (HMEC) with a PBR-322-based plasmid containing the coding region for the simian virus 40 A gene product, large T antigen, and succeeded in immortalizing them. These cells, termed CDC/EU.HMEC-1 (HMEC-1), have been passaged 95 times to date and show no signs of senescence, whereas normal microvascular endothelial cells undergo senescence at passages 8-10. HMEC-1 exhibit typical cobblestone morphology when grown in monolayer culture, express and secrete von Willebrand's Factor, take up acteylated low-density lipoprotein, and rapidly form tubes when cultured on matrigel. HMEC-1 grow to densities three to seven times higher than microvascular endothelial cells and require much less stringent growth medium. HMEC-1 will grow in the absence of human serum, whereas microvascular endothelial cells require culture medium supplemented with 30% human serum. These cells express other cell-surface molecules typically associated with endothelial cells, including CD31 and CD36 and epitopes identified by monoclonal antibodies EN4 and PAL-E. They also express the cell adhesion molecules ICAM-1 and CD44 and following stimulation with interferon-gamma express major histocompatibility complex class II antigens. HMEC-1 specifically bind lymphocytes in cell adhesion assays. Thus HMEC-1 is the first immortalized human microvascular endothelial cell line that retains the morphologic, phenotypic, and functional characteristics of normal human microvascular endothelial cells.

Antigens, Differentiation, Myelomonocytic↗
PubMed1992

Expression and modulation of the vitronectin receptor on human dermal microvascular endothelial cells.

Microvascular endothelial cells express a variety of cell-surface integrins in vivo and in vitro with varying affinities for matrix proteins. The vitronectin receptor (VnR), a complex of the alpha v and beta 3 integrin chains, is capable of binding to a variety of matrix proteins that are deposited in injured tissues, including vitronectin, fibrinogen, and thrombin. Staining of frozen sections of human skin with antibodies recognizing the VnR and examination by immunofluorescence microscopy demonstrates staining in a vascular pattern suggesting in vivo expression of the vitronectin receptor on endothelial cells. Examination of pure cultures of human dermal microvascular endothelial cells (HDMEC) by flow-cytometric analysis and enzyme-linked immunosorbent assay confirmed that HDMEC also express cell surface VnR complex in vitro. Stimulation of human dermal microvascular endothelial cells in vitro with agents that stimulate protein kinase C resulted in dose- and time-dependent increases in expression of alpha v and beta 3 integrin chains. Additionally, stimulation with basic fibroblast growth factor induced similar increases, but stimulation with transforming growth factor-beta or interleukin-1 alpha failed to increase VnR expression. Increases in cell-surface VnR expression also correlated with an increased ability of microvascular endothelial cells to bind to vitronectin, but not fibronectin-coated surfaces. Although increases in cell-surface expression of beta 3 paralleled increases in expression of cell-surface alpha v, regulation of mRNA expression was distinct for each chain. These data suggests that microvascular endothelial cells express the VnR complex in vivo, that the cell-surface expression of this integrin on dermal microvascular endothelial cells can be regulated, and that this regulation may be important in cell adherence, cell migration, and wound healing.

Blotting, Northern↗
PubMed1979

Pruritic urticarial papules and plaques of pregnancy.

We report an intensely pruritic cutaneous eruption that occurs in the third trimester of pregnancy. The clinical manifestations include erythematous urticarial papules and plaques that begin on the abdomen and spread to involve the thighs and occasionally the buttocks and arms. This dermatosis appears to be clinically distinct from previously described pruritic eruptions occurring in pregnancy. Biopsy specimens of the lesions show two histological patterns. We propose that this entity be termed "pruritic urticarial papules and plaques of pregnancy (PUPPP)".

Abdomen↗
PubMed1979

Defective reticuloendothelial system Fc-receptor function in systemic lupus erythematosus.

To determine whether reticuloendothelial-system immunospecific Fc-receptor function is abnormal in patients with systemic lupus erythematosus, we studied the clearance of IgG-sensitized 51Cr-labeled erythrocytes by these splenic macrophage membrane receptors in 15 untreated patients. Fc-specific clearance rates were strikingly abnormal in 13 of 15 patients (half-times ranging from 80 to 2256 minutes, P less than 0.001 as compared to controls). Abnormal clearances correlated with immune-complex levels (as measured by the C1q-binding assay) and with disease activity. C1q-binding activity and anti-DNA titers also correlated with disease activity. The correlations of C3, C4, CH50 and factor B with abnormal clearance and disease activity were weaker or nonexistent. The significant correlations among clearance, disease activity and C1q-binding activity suggest that the defect in Fc-receptor function may lead to the prolonged circulation of immune complexes, thereby contributing to tissue deposition and damage.

Adult↗
PubMed1979

Immunologic reactivity in the hypereosinophilic syndrome.

Because previous studies have suggested an important link between eosinophilia and immunologic reactivity, we investigated various components of the immune system in a large number of patients with the idiopathic hypereosinophilic syndrome (HES) to elucidate a possible role for immunologic phenomena in the etiology and pathogenesis of this disease. Immunoglobulin G, A, or M levels were only rarely abnormal. However, in 8 of 21 (38%) patients with HES, IgE levels were markedly elevated suggesting an association of an IgE-mediated mechanism with eosinophilia in this subgroup. Severe dermatographism was present in three fourths of patients, and 2 patients with intermittently elevated histamine levels manifested an unusual form of immediate-pressure urticaria. Serum complement determinations showed elevated C4 and C3 levels in 27% and 77% of patients, respectively. Antigen-antibody complexlike material measured by C1q binding was elevated in the serum of 7 of 22 (32%) patients; this finding may relate to the known ability of eosinophils to avidly phagocytose antigen-antibody complexes. When compared with normals, lymphocytes from patients with HES showed a variety of abnormalities of lymphocyte surface receptors and lymphocyte function. Thus, patients with HES demonstrate a variety of immunologic abnormalities which may be related primarily or secondarily to the pathogenesis of this syndrome.

Antigens, Surface↗
PubMed1979

Sjögren's syndrome: a defect in reticuloendothelial system Fc-receptor-specific clearance.

To determine the functional status of reticuloendothelial system Fc receptors in patients with Sjögren's syndrome, we studied the rate of clearance from the circulation of 51Cr-labeled IgG-sensitized autologous erythrocytes in 19 patients. Fc-receptor-mediated clearance was abnormal in 12 of the 19 patients, with half-lives ranging from 80 to 356 min. There was a significant correlation between clearance rates and clinical manifestations of disease. Clearance rates tended to be normal in patients with disease limited to exocrine glands and abnormal in patients with widespread disease. In contrast, there were no correlations between the rate of clearance of IgG-sensitized erythrocytes and serum immune complex levels, serum complement component levels, or rheumatoid factor titers. The striking correlation between clearance rates and disease manifestations suggests that decreased clearance of immune complexes by defective reticuloendothelial system Fc receptors may contribute to disease pathogenesis.

Adult↗
PubMed1979

Circulating immune complexes in acute schistosomiasis.

The sera of patients with acute and chronic schistosomasis were tested for the presence of circulating immune complexes with the 125I-Clq binding assay. Fourteen out of fifteen (93%) patients with acute schistosomiasis had elevated 125I-Clq binding activity, while only two out of eleven (18%) patients with chronic disease had C1q binding complexes. This difference was significant (P less than 0.001) and paralleled the degree of clinical didsease activity between the two groups of patients. IgG and IgM were readily detected in all of these circulating complexes but the specific parasite antigens initiating their formation could not be defined. The level of circulating immune complexes was inversely correlated with the absolute eosinophil counts for individuals in the acutely infected group, an observation compatible wiht the hypothesis that a functional role for the eosinophil is the destruction and elimination of immune complexes.

Acute Disease↗
PubMed1979

Necrolytic migratory erythema without glucagonoma.

Two patients with clinical and histologic findings consistent with necrolytic migratory erythema are presented. Unlike previously described patients with this disorder, neither patient had substantially elevated glucagon levels nor an associated pancreatic islet cell tumor. The cause of the skin disease in these patients remains unknown but may be related to the underlying small-bowel disorder present in both.

Adult↗
PubMed1978

Antibodies to type II collagen in relapsing polychondritis.

Relapsing polychondritis is a disorder of unknown cause characterized by the destruction of cartilage. To test the hypothesis that immunologic mechanisms are involved in the pathogenesis of relapsing polychondritis, we analyzed the serum of 15 patients for the presence of antibodies to cartilage. Antibodies to Type II (cartilage) collagen were found in the serum of five patients at the time of acute symptoms. No antibodies were detected either to cartilage proteoglycan or to other collagen types. The antibodies were detected at the onset of the disease and their titers appeared to correlate with severity of disease. Circulating immune complexes were also detected in the serum of these patients. Our findings support an immunologic involvement in this condition.

Acute Disease↗
PubMed1978

Immune complex glomerulonephritis in sicca syndrome.

In three patients with the sicca syndrome (Sjögren's syndrome), who were followed for one to seven years, glomerulonephritis developed. None of these patients fulfilled the diagnostic criteria for systemic lupus erythematosus. All of these patients had circulating immune complexes as detected by the Clq binding assay. Glomerular histology by light and electron microscopy revealed changes compatible with membranoproliferative glomerulonephritis in two of the patients and membranous glomerulonephritis in the third. All patients showed rapid improvement in renal function following moderate doses of corticosteroids. In addition, the treatment decreased the level of circulating immune complexes in two patients who were followed for a sufficient period of time.

Adult↗
PubMed1978

Evaluation of the adverse effects of long-term hyposensitization.

This study was undertaken to determine if long-term hyposensitization causes late sequelae, particularly those reflecting aberrant immunologic responses. Atopic individuals receiving five or more years of hyposensitization with allergenic extracts showed no increased autoimmune, collagen vascular, or lymphoproliferative disease. In addition, chronic hyposensitization did not have adverse effects on immunologic reactivity as assessed by a number of immune parameters. Particularly noteworthy was the absence of immune complexes in the serum of patients undergoing long-term hyposensitization. This study represents the first systematic investigation of potential adverse effects of long-term hyposensitization.

Adolescent↗