Biomedical subjects

S Bernasconi

Publications and source records attributed to S Bernasconi.

At least 181 records · Page 10Linked to original sources

PubMed1992

Expression of adhesion molecules and chemotactic cytokines in cultured human mesothelial cells.

The mesothelium is a flat epithelial lining of serous cavities that could gate the traffic of molecules and cells between the circulation and these body compartments. The present study was designed to elucidate the capacity of mesothelial cells to express adhesion molecules and chemoattractant cytokines, two fundamental mechanisms of regulation of leukocyte recruitment. Cultured human mesothelial cells express appreciable levels of intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), and these were increased by in vitro exposure to tumor necrosis factor (TNF), interferon gamma (IFN-gamma), or TNF and IFN-gamma. Interleukin 1 (IL-1) was a less consistent stimulus for adhesion molecule expression in vitro. Unlike endothelial cells, used as a reference cell population, resting or stimulated mesothelial cells did not express E-selectin and ICAM-2, as assessed by flow cytometry. Analysis of VCAM-1 mRNA by reverse transcriptase and polymerase chain reaction using appropriate primers revealed that mesothelial cells expressed both the seven- and the six-Ig domain transcripts, with predominance of the longer species. Monocytes bound appreciably to "resting" and, to a greater extent, to stimulated mesothelial cells. Monocytes exposed to IFN-gamma and lipopolysaccharide, used as prototypic activation signals, showed increased capacity to bind mesothelial cells. Anti-CD18 monoclonal antibody significantly inhibited binding of monocytes to mesothelial cells, and this blocking effect was amplified by anti-very late antigen 4. Mesothelial cells were able to express the chemotactic cytokines IL-8 and monocyte chemotactic protein 1 at the mRNA and protein levels. These results indicate that mesothelial cells can express a set of adhesion molecules (ICAM-1 and VCAM-1) overlapping with, but distinct from, that expressed in vascular endothelium (ICAM-1, ICAM-2, VCAM-1, E-selectin), and that these are functionally relevant for interacting with mononuclear phagocytes. The regulated expression of adhesion molecules and chemotactic cytokines by mesothelial cells is probably important in inflammatory and immune reactions that involve serous cavities, such as the long-known macrophage appearance and disappearance reactions.

Antigens, CD↗

PubMed1992

Molecules involved in the adhesion and cytotoxicity of activated monocytes on endothelial cells.

Our study was designed to investigate the surface molecules involved in the adhesion and cytotoxicity of activated human monocytes on resting and IL-1-stimulated endothelial cells (EC). Monocytes, exposed to the prototypic activating stimuli IFN-gamma and LPS, showed increased binding to resting and IL-1-treated EC. Activated monocytes were cytotoxic for resting and IL-1-treated EC in a 24- to 48-h [3H]TdR release assay. Anti-CD18 mAb significantly inhibited binding of monocytes on EC: in particular they caused 59 and 22% inhibition of adhesion of activated monocytes to resting and IL-1-stimulated EC, respectively. Anti-VLA4 mAb had little or no effect on binding when used alone, but combined use with anti-CD18 revealed an important role for this adhesion pathway: in particular, VLA4-dependent adhesion accounted for 40% of the binding of activated monocytes on IL-1-treated EC. Anti-CD18 mAb caused similar inhibition (77 and 81%) of the cytotoxicity of activated monocytes on resting and IL-1-treated EC in spite of the fact that this pathway accounted for only 22% of binding to activated EC. Moreover, anti-VLA4 mAb, alone or in combination with anti-CD18, had no effect on cytotoxicity. These results suggest that adhesion of activated monocytes to activated EC involves the CD18- and VLA4-dependent pathways, but that the former is dominant for the expression of cytotoxicity. Thus, in the ensemble of adhesion molecules available for interaction between endothelium and activated monocytes, the hierarchy of their importance may vary for different functions.

Antibodies, Monoclonal↗

PubMed1992

Heterogeneous susceptibility of human melanoma clones to monocyte cytotoxicity: role of ICAM-1 defined by antibody blocking and gene transfer.

Five clones derived from the same human malignant melanoma lesion were studied for their susceptibility to killing by human monocytes activated by exposure to interferon (IFN)-gamma and lipopolysaccharide. Melanoma clones were heterogeneous in their susceptibility to human monocyte cytotoxicity, with one clone (2/21) exhibiting extremely low levels of lysis. The different levels of susceptibility to monocyte cytotoxicity were not accounted for by susceptibility or resistance to monokines [tumor necrosis factor (TNF), interleukin (IL)-1 and IL-6] because: (a) these effector molecules had little (TNF) or no (IL-1 and IL-6) cytolytic activity under these conditions; and (b) anti-TNF antibodies had marginal effects on cytotoxicity. Monocytes bound less to resistant than to susceptible melanoma cells. Monocyte-resistant 2/21 melanoma cells expressed substantially lower levels of ICAM-1 and VLA-4 than susceptible cells. Anti-CD18 and, to a lesser extent, anti-ICAM-1 mAb inhibited binding and cytotoxicity of human monocytes on malignant melanoma whereas anti-VLA-4 had no inhibitory action. Transfection of the ICAM-1 gene under the control of a constitutive promotor resulted in high levels of expression of ICAM-1 in 2/21 melanoma cells and, concomitantly, in augmented susceptibility to activated monocyte cytotoxicity. The augmented killing of ICAM-1 transfected 2/21 cells was inhibited by anti-ICAM-1 mAb. These results demonstrate that the CD18-ICAM-1 adhesion pathway can play an important role in the expression of human monocyte cytotoxicity on melanoma target cells and that heterogeneity in expression of ICAM-1 can underlie differences in susceptibility to tumoricidal activity.

Animals↗

PubMed1992

In search of specific cytotoxic T lymphocytes infiltrating or accompanying human ovarian carcinoma.

Lymphocytes infiltrating human ovarian carcinoma obtained directly from the tumour mass (tumour-infiltrating lymphocytes, TIL) or from the carcinomatous ascites (tumour-associated lymphocytes, TAL) were expanded in vitro in long-term cultures with interleukin-2 and tested for their specific cytolytic activity. Killing of the autologous tumour was detected only in a proportion of the patients, less frequently in TIL compared to TAL. In fact two out of ten TIL and four out of nine TAL cultures tested showed significant levels of lysis against the autologous tumour. This cytotoxic activity was not restricted to the autologous tumour, as other tumour cell lines, including non-ovarian ones, were lysed as well. The cultures that were not cytotoxic against the autologous tumour were in most cases able to lyse other tumour cell lines of ovarian or other histology. Cloning of TIL from one patient was performed: of 22 clones tested, 4 displayed higher cytotoxicity against the autologous tumour compared to the uncloned population and 3 out of these 4 did not kill an irrelevant carcinoma cell line. In order to stimulate the expansion of putative specific effectors we performed mixed lymphocyte/tumour cultures (MLTC) with autologous or allogeneic tumour cells. No stimulation of cytotoxicity against the autologous tumour was detected after MLTC in nine different TAL populations, using autologous or allogeneic tumours as stimulators. On the contrary, peripheral blood lymphocytes from two patients after MLTC with the autologous tumour showed increased killing of the autologous and decreased killing of an allogeneic target. In conclusion TIL and TAL from ovarian carcinoma expanded in vitro with interleukin-2 usually have non-MHC-restricted cytotoxicity and variable degrees of reactivity against the autologous tumour. A preferential killing for the autologous tumour was not observed even after MLTC. These results do not exclude the existence of tumour-specific cytotoxic T lymphocytes in ovarian carcinoma; nevertheless they suggest that putative specific effectors have very low frequency and that culture techniques for expanding their growth more selectively are still to be optimized.

Cells, Cultured↗

PubMed1992

Inhibitory effect of recombinant intracellular interleukin 1 receptor antagonist on endothelial cell activation.

This investigation was designed to elucidate whether an intracellular version of interleukin 1 receptor antagonist (icIL-1ra) interferes with the action of IL-1 at the level of vascular cells. Recombinant icIL-1ra inhibited the IL-1-induced production of IL-6, IL-8 and monocyte chemotactic protein by human endothelial cells (HEC). Moreover, icIL-1ra inhibited induction of adhesion molecules by IL-1. Endotoxin lipopolysaccharide (LPS), an IL-1 inducer, stimulated a spectrum of functions in EC similar to that activated by IL-1, but icIL-1ra did not interfere with the LPS activation of EC. This observation suggests that induction of extracellular IL-1 is not an important intermediate event in the response of EC to LPS. Unlike LPS-stimulated monocytes, EC exposed to different inducers did not express appreciable levels of IL-1ra mRNA transcripts as assessed by northern blot analysis. IL-1ra produced by mononuclear phagocytes, represents a negative regulator circuit of the action of IL-1 on EC and could be important in the control of vascular participation in inflammation and immunity.

Cell Adhesion Molecules↗

PubMed1992

Molecular analysis of the androgen receptor gene in 52 patients with complete or partial androgen insensitivity syndrome: a collaborative study.

In patients with androgen insensitivity syndrome (AIS), RFLP study of the androgen receptor gene made it possible to analyze whether deletions or mutations could be responsible for abnormalities in androgen responsiveness. We studied RFLPs of DNA from 25 46,XY patients with partial AIS (PAIS), defined as a concentration of androgen receptor in genital-skin fibroblasts less than 340 fmol/mg DNA, and DNA from 27 46,XY patients with complete AIS (CAIS) with no detectable androgen receptor site. DNA samples were digested with BamHI, EcoRI, HindIII and TaqI restriction enzymes and hybridized with three cDNA probes covering the three domains of the androgen receptor. When we had the maternal and an unaffected brother's DNA, we analyzed the two androgen receptor gene polymorphisms described, the HindIII and the exon 1 CAG repeat polymorphisms, in order to distinguish the two maternal X chromosomes, and to detect carriers of AIS. We did not find any large deletion among the 52 patients. We observed a heterozygous mother in 3 of 14 families studied with the HindIII polymorphism, and in 12 of 25 families using the exon 1 CAG repeat polymorphism. This study suggests that in AIS, abnormalities in androgen receptor response could be related to point mutations or microdeletions rather than to gross structural alterations of the androgen receptor gene. Furthermore, unless the point mutation has been described, exon 1 and HindIII polymorphism studies would enable the identification of carriers in 50% of families, and the prenatal diagnosis of AIS.

Androgens↗

PubMed1992

Congenital anorchia: natural history and treatment.

This paper discusses the definition, pathogenesis, diagnosis and treatment of congenital anorchia. It concludes that preparations containing esters of testosterone are preferable to synthetic derivatives for long-term treatment as they are metabolized in the same way as endogenous testosterone. In addition, it appears that recommended doses for replacement therapy are lower than previously suggested. An ideal formulation of testosterone for use in androgen replacement therapy is not currently available.

Adolescent↗

PubMed1992

Natural history of premature pubarche: an auxological study.

The natural history of girls with premature pubarche is reported to be normal, but the effects on puberty and on final height are not well documented. We assessed the outcome of a group of girls with premature pubarche from two Latin populations in whom 21-hydroxylase deficiency had been ruled out by an ACTH test. Patients comprised 127 girls (70 Northern-Italian and 57 Northern-Spanish), of whom 69 had entered puberty and 38 had attained adult height. Height, bone age, onset and progression of puberty, height prognosis, adult height, and baseline plasma androgen levels were evaluated. Advanced skeletal maturation and tall stature were constant features during the first years of follow-up and subsequently declined. Puberty began at 9.7 +/- 0.9 yr, and age at menarche (12.0 +/- 1.0 yr) was comparable to maternal and population menarcheal ages. The appearance and chronology of pubertal milestones in both populations were very similar. Adult heights correlated with the height prognosis at diagnosis and at onset of puberty, and were above midparental heights. Premature pubarche produces a transient acceleration in growth and bone maturation with no negative effects on the onset and progression of puberty and final height.

Adolescent↗

PubMed1992

GH response to GHRH, insulin, clonidine and arginine after GHRH pretreatment in children.

To determine whether differences in the neuroendocrine control of GH are present between children and adult subjects, the GH response to GHRH (1 microgram/kg) (group 1), insulin-induced hypoglycemia (0.1 U/kg iv) (group 2), clonidine (150 micrograms/m2 po) (group 3) and iv arginine (0.5 g/kg in 30 min) (group 4) after GHRH pretreatment (1 microgram/kg) was studied in 26 short-stature normal children (mean age 10.2 years). The results were compared with historical data in adults. No differences were present among mean peak GH levels after the first and second stimuli in groups 1, 2 and 3, while in group 4 the GH response to arginine administration was lower than that obtained after the initial GHRH (0.43 +/- 0.04 vs 0.9 +/- 0.13 nmol/l). Moreover, comparing the GH peak values following the second stimulus, it appears that the greatest GH responses were elicited by GHRH (1.31 +/- 0.23 nmol/l) and clonidine (1.11 +/- 0.22 nmol/l), while the lowest was elicited by arginine (0.43 +/- 0.04 nmol/l). In adults, sequential GHRH administration leads to inhibition of the response of the somatotropes, probably mediated by an increase in hypothalamic somatostatin. Our results confirm that after GHRH prestimulation GHRH elicits a significant GH response suggesting that activation of the somatostatinergic tone is less effective in children. This hypothesis also explains the low GH response to arginine which acts selectively through somatostatin inhibition.

Adolescent↗

PubMed1992

Regulated expression of vascular cell adhesion molecule-1 in human malignant melanoma.

Expression of the endothelial adhesion molecule VCAM-1 was studied in human malignant melanoma lines by flow cytometry. Clones 2/4 and 2/14 (derived from the same lesion) had appreciable levels of VCAM-1 expression, whereas clone 2/21 and the lines A2058, Mel24, and A375 were negative. Clone 2/14 was selected for further analysis. Exposure to tumor necrosis factor (TNF) markedly augmented VCAM-1 on melanoma cells. Surface VCAM-1 was associated with expression of specific transcripts that were augmented by TNF. Analysis by reverse transcriptase and polymerase chain reaction using appropriate primers revealed that TNF-stimulated melanoma cells expressed both 7 and 6 immunoglobulin domain transcripts with predominance of the longer species. Tumor necrosis factor--stimulated melanoma cells bound more VLA-4-expressing cells (melanoma and monocytes) than resting tumor cells and anti-VCAM-1 monoclonal antibodies significantly inhibited binding, thus suggesting that surface VCAM-1 on melanoma is functional. Analysis of melanoma tissue sections demonstrated that VCAM-1 is not a marker of transformation of melanocytes because it can be detected in benign nevi. Although, unlike ICAM-1, VCAM-1 is not correlated with tumor progression, its expression in a fraction of primary melanomas indicates that it may play a role in regulating host immune response and homotypic interactions in some malignant melanomas.

Base Sequence↗

PubMed1992

Endothelial leukocyte adhesion molecule-1-dependent adhesion of colon carcinoma cells to vascular endothelium is inhibited by an antibody to Lewis fucosylated type I carbohydrate chain.

Endothelial leukocyte adhesion molecule-1 (ELAM-1) has been determined to be the mediator of adhesion of colon carcinoma cells to interleukin-1 (IL-1)-activated endothelial cells. To identify ELAM-1 ligand in colon carcinoma cells, we have screened a series of 11 monoclonal antibodies directed to these cells and found that only one MBr8 was able to inhibit the IL-1-induced increment in adhesion of HT29 and of SW948 colon carcinoma lines to endothelial cells. In contrast, MBr8 did not bind to polymorphonuclear cells, monocytes, and lymphocytes and did not inhibit polymorphonuclear adhesion to IL-1-activated endothelial cells. As expected, an ELAM-1 monoclonal antibody strongly inhibited IL-1 induced increment of adhesion of HT29, SW948, and polymorphonuclear cells. As negative control, MG63 osteosarcoma cells were used. These cells adhere more efficiently to IL-1 activated endothelial cells but MBr8 and ELAM-1 monoclonal antibodies did not affect their adhesion. The effect of MBr8 was also tested in an experimental system in vivo. As described previously, radiolabeled HT29 cell retention in the lung of nude mice was increased in animals given IL-1. MBr8 administration to nude mice or pretreatment of tumor cells with it inhibited this effect. These data suggest that cell adhesion to ELAM-1 might be mediated by different, cell type specific, sugar ligands.

Antibodies, Monoclonal↗

PubMed1991

Involvement of leukocyte (beta 2) integrins (CD18/CD11) in human monocyte tumoricidal activity.

Appropriately activated mononuclear phagocytes mediate contact-dependent tumoricidal activity. Adhesion structures involved in contact-dependent tumor cytotoxicity have not been defined. The present study was aimed at identifying the adhesion structures involved in the tumoricidal activity of activated (IFN-gamma + LPS) human monocytes. Tumor cells of different histological origin were used as targets in a 48-hr cytolysis assay. Anti-CD18 (integrin beta 2 chain) monoclonal antibodies (MAbs) substantially (50-80%) inhibited human monocyte cytotoxicity. When the role of different a-chains was studied, anti-alpha L (CD11a, LFA1), anti-alpha M (CD11b, Mac-1) and anti-alpha X (CD11c, p150,95) caused marginal inhibition, but the effect of the 3 combined was comparable to that of anti-CD18. Anti-CD18 MAb did not affect the release of various cytotoxic molecules (e.g. TNF) by activated human monocytes. Activated monocytes showed augmented binding to target cells and anti-CD18 MAb inhibited the binding of resting and activated monocytes to tumor target cells. While IFN-gamma alone augmented expression of leukocyte integrins and LPS had no effect, the 2 activation signals, combined for optimal stimulation of tumoricidal activity, resulted in no appreciable increase in these leukocyte adhesion molecules, as assessed by flow cytometry. Our results suggest that the augmented CD18-dependent binding of activated monocytes on tumor cells depends mainly upon changes in the adhesive properties of these molecules rather than upon increased numbers on the cell surface. Anti-ICAM-1 MAb significantly reduced monocyte cytotoxicity on tumor cells, which is consistent with a role of the CD11/CD18 adhesion pathway. These results implicate "activated" leukocyte (beta 2) integrins (CD11/CD18) as important adhesion molecules in the contact-dependent tumoricidal activity of human monocytes.

Antibodies, Monoclonal↗

PubMed1991

Heterogeneity in human melanoma cell adhesion to cytokine activated endothelial cells correlates with VLA-4 expression.

Tumor cell attachment to endothelial cells (EC) is one of the critical steps of the metastatic process. It was previously reported that interleukin 1 treatment of EC induces expression of membrane molecules that promote tumor cell adhesion. In this paper we report that a panel of six clones isolated from a human metastatic melanoma presented a marked heterogeneity in their ability to adhere to interleukin 1 activated EC. This was correlated with integrin VLA-4 expression by the clones. Antibodies directed to VLA-4 and to its endothelial ligand INCAM110/VCAM-1 abolished interleukin 1 induced increase in melanoma cell adhesion to EC. These data demonstrate intratumor heterogeneity in the expression of VLA-4 and that this can represent a crucial determinant of tumor cell interaction with EC during secondary spread.

Cell Adhesion↗

PubMed1991

Effectiveness of growth-promoting therapies. Comparison among growth hormone, clonidine, and levodopa.

The ability of growth hormone, clonidine, and levodopa to stimulate growth was compared in short and slowly growing children randomly assigned to different treatment regimens for 6 months. There were 10 children in each group, and 10 additional subjects served as controls. Growth hormone improved mean height velocity, height velocity SD score, and height SD score. The mean height velocity and height velocity SD score were significantly increased by clonidine, while levodopa only enhanced the mean height velocity SD score of the treated children. Moreover, in nine patients (90%) receiving growth hormone, two (20%) receiving clonidine, and one (10%) receiving levodopa, the height velocity was raised by more than 2 cm/y. The increments in height velocity and height SD score were greatest in the growth hormone group. Clonidine induced an increase in height velocity significantly different from that in control children only. In the control group, there was a significant reduction of height SD score with time.

Body Height↗

PubMed1991

Role of manganese in MG-63 osteosarcoma cell attachment to fibrinogen and von Willebrand factor.

Some integrin receptors have been reported to be functionally distinct in different cell types. In endothelial and melanoma cells, the vitronectin receptor, alpha v beta 3 binds fibrinogen (fg) and von Willebrand factor (vWf) in addition to vitronectin itself, whereas it fails to do so in MG-63 osteosarcoma cells. In this report, it is shown that, in the presence of Mn2+, MG-63 cells attach more efficiently to vitronectin and acquire the de novo capacity to adhere to fg- and vWf-coated surfaces. The latter phenomenon occurs with full cell spreading, F-actin microfilament organization, and alpha v and beta 3 clustering at focal contacts. In contrast, beta 1 and beta 5 do not localize to adhesion plaques under the same experimental conditions. An antiserum to the beta 3 chain and a synthetic peptide containing the sequence Gly-Arg-Gly-Asp-Ser-Pro block MG-63 attachment to fg and vWf in the presence of Mn2+. The minimal active concentration of Mn2+ is in the range of 0.1 to 1 microns. These data suggest that the acquired capacity of MG-63 to attach to fg and vWf in the presence of Mn2+ is mediated by alpha v beta 3 and that differences in alpha v beta 3 receptor specificity may be modulated by exogenous factors.

Amino Acid Sequence↗

PubMed1991

Role of beta 1 integrins in tumor cell adhesion to cultured human endothelial cells.

We investigated the effects of beta 1 integrins on tumor cell (TC) adhesion to unstimulated and interleukin-1 (IL-1) activated endothelial cells (EC). IL-1 treatment (20 units/ml for 6 hours) of cultured human umbilical vein EC significantly increased adhesion of seven human TC lines of different origin. A goat antiserum raised to purified alpha 5 beta 1 integrin abolished the IL-1 induced increment in adhesion of two osteosarcomas, one melanoma, one lung, and one kidney carcinoma, whereas it did not affect adhesion of two colon carcinoma cell lines. Further studies were performed on MG63 osteosarcoma cells. Adhesion of MG63 osteosarcoma cells to EC was dependent on time of EC treatment with IL-1: it was maximal at 12 hours and declined at 24 hours. alpha 5 beta 1 antiserum blocked IL-1 induced increase in MG63 adhesion at any time of EC treatment. This effect appears to be mainly directed to MG63 integrins since selective incubation of the antiserum with EC, but not with MG63, did not modify TC adhesion. Using a series of antibodies to different alpha and beta chains, we found that only monoclonal antibodies (mAb) to alpha 4, alpha 5, and beta 1 could inhibit MG63 adhesion to IL-1 activated EC, whereas alpha 2, alpha 6, and beta 3 antibodies were ineffective. Antibodies to fibronectin had very little activity on MG63 adhesion to EC matrix and did not significantly affect MG63 adhesion to control or IL-1 treated EC. Antibodies to alpha 4, alpha 5, and beta 1 were only partially effective in inhibiting MG63 adhesion to EC matrix. These data indicate that the capacity of alpha 4 beta 1 and alpha 5 beta 1 integrins to bind fibronectin contributed very little to MG63 adhesion to EC. The importance of beta 1 integrins in promoting a direct interaction between EC and MG63 was further shown by inhibition of rosette formation among these cells in suspension by the alpha 5 beta 1 antiserum. Only a VCAM-1/INCAM110 mAb, but not ELAM-1 or ICAM-1 mAbs, could inhibit MG63 adhesion to IL-1 activated EC. Overall these data indicate that at least two members of the beta 1 integrin subfamily (alpha 4 beta 1 and alpha 5 beta 1) are involved in MG63 adhesion to cytokine treated EC. This integrin function might be important at early stages of TC interaction with the vessel wall.

Antibodies, Monoclonal↗

PubMed1990

3-Methylcholanthrene induces differential inhibition of humoral and cell mediated immune responses in mice of different ages.

C57B1/6 mice aged 2-3 and 13-14 months were treated i.p. with 3-methylcholanthrene. A single dose of 25 mg/kg reduced primary antibody production to the T-dependent antigen sheep red blood cells by 20% in mice aged 2-3 months and by 90% in 13-14-month-old animals. The same treatment did not reduce antibody production to the T-independent antigen pneumococcal polysaccharide type III in young mice, but reduced this response by 50% in 13-14-month-old animals. Blastogenesis to concanavalin A, phytohemagglutinin and alloantigens, that is mediated by T lymphocytes, was consistently reduced in young animals but only marginally affected, when at all, in 13-14-month-old mice. Blastogenesis to lipopolysaccharide, mediated by B lymphocytes, was reduced in mice of both ages, though in older mice it was affected later than in younger animals. Addition of 3-methylcholanthrene in vitro increased T lymphocyte responses equally in mice of both ages and did not modify B lymphocyte proliferation. Results presented here show that older mice are not necessarily more susceptible to all types of immunosuppression induced by a xenobiotic like 3-methylcholanthrene and that the sensitivity of the different facets of the immune response can change with aging.

Age Factors↗

PubMed1990

Cytotoxicity of activated monocytes on endothelial cells.

Unstimulated human monocytes did not express appreciable levels of cytotoxicity on normal human umbilical vein endothelial cells (EC) in a 24-48 hr TdR release assay. On activation with IFN-gamma and LPS, monocytes had appreciable cytotoxicity on EC. Monocyte cytotoxicity on EC was not dependent on the presence of contaminating lymphoid cells. Recombinant TNF, IL-1, and IL-6 as well as monocyte supernatants did not exert a cytotoxic effect on EC. Moreover, anti-TNF, anti-IL-1, and anti-IL-6 antibodies, as well as scavengers of reactive oxygen intermediates, did not affect the cytotoxicity of activated monocytes on EC. Antibodies against the beta-chain (CD18) of leukocyte integrins inhibited the adhesion and cytotoxicity of activated monocytes on EC. Pretreatment of EC with IL-1 augmented the adhesion of monocytes on EC. Normal monocytes were not cytotoxic on IL-1-pretreated EC and IL-1 treatment did not increase the susceptibility of EC to activated monocytes. Thus adhesion is necessary but not sufficient for monocyte killing of EC. Anti-alpha L (LFA-1) antibodies markedly reduced monocyte cytotoxicity on EC, although anti-alpha X (p150) antibodies had only a modest effect. Anti-alpha M (Mac-1/CR3) antibodies were intermediate inhibitors of EC killing by activated monocytes. Thus, alpha L, beta 2 (LFA-1), and, to a lesser extent, alpha M, beta 2 (Mac-1/CR3) and alpha X, beta 2 (p 150, 95) integrins are the main adhesive structures involved in the cytotoxic interaction of activated monocytes with EC. Monocyte-mediated damage of EC could play a role as a mechanism of tissue injury under conditions of local or systemic activation of mononuclear phagocytes.

Antigens, Differentiation↗