Effect of C1-esterase-inhibitor on capillary leak and inflammatory response syndrome during arterial switch operations in neonates.

OBJECTIVE: To determine if prophylactic administration of C1-esterase-inhibitor would have a beneficial effect on postoperative weight gain and the inflammatory response in neonates undergoing cardiac surgery with cardiopulmonary bypass (CPB). DESIGN: Randomized, double-blinded study. SETTING: University-affiliated heart center. PARTICIPANTS: Twenty-four neonates with transposition of the great arteries. INTERVENTIONS: In group inhibitor (INH) patients (n = 12), 100 IU/kg of C1-esterase-inhibitor (Berinert) was given 30 minutes before CPB. In group placebo (P) patients (n = 12), placebo was administered instead. Interleukin (IL)-6, C3a anaphylatoxin, C1 activity, prekallikrein, Hageman factor, D-dimers, and clinical parameters were measured 6 times perioperatively. MEASUREMENTS AND MAIN RESULTS: All 24 patients had an uneventful clinical course. Mean arterial pressure and pulmonary oxygenation after CPB were superior in group INH patients. The weight gain on postoperative days 1 to 4 was significantly less in group INH patients compared with group P (55 +/- 59 g vs. 340 +/- 121 g, day 1). The concentration of IL-6 (76 +/- 17 pg/mL vs. 262 +/- 95 pg/mL during CPB) was significantly lower in group INH patients compared with group P patients. In contrast, no influence on C3a anaphylatoxin and coagulation factors was found. CONCLUSION: Prophylactic application of C1-esterase-inhibitor in neonates undergoing arterial switch operations produces less inflammatory response compared with placebo. This difference may have contributed to improved clinical parameters, including less weight gain postoperatively.

Local administration of dendritic cells inhibits established breast tumor growth: implications for apoptosis-inducing agents.

Dendritic cells (DCs) can efficiently acquire foreign antigen(s) from apoptotic cells and induce MHC class I-restricted, antigen-specific CTLs. An accumulation of DCs within solid tumor masses in situ has been associated indirectly with a more favorable prognosis. Therefore, DCs may offer an efficient means for triggering immune responses within tumors, particularly in those masses containing significant apoptosis. We examined whether delivery of DCs could, alone, impact on the progressive growth of a tumor with a relatively high apoptotic index. We detected significant early apoptosis within the mass of a s.c. growing murine MT-901 breast carcinoma. DCs could efficiently engulf MT-901 tumor apoptotic cells in vitro. Intratumoral injections of syngeneic but not allogeneic DCs resulted in significant inhibition of MT-901 tumor growth. Histological examination of the tumor revealed intense mononuclear cell infiltration during and after DC injections. Tumor growth inhibition was relatively radiosensitive and dependent on host-derived CD8+ T cells. The baseline level of tumor apoptosis could be increased substantially by tumor necrosis factor alpha administration, leading to a greater DC-mediated antitumor effect. The antitumor effect could also be enhanced by first pulsing DCs with the foreign helper protein, keyhole limpet hemocyanin, prior to intratumoral delivery and combining it with the systemic administration of interleukin 2. Splenocytes from treated animals showed heightened levels of specific CTL activity and production of cytokines. The level of in situ tumor apoptosis appears to play a critical role in DC-mediated antitumor effects. The potential implication of these findings in DC-based tumor therapy strategies is discussed.

Recruitment of non-patient volunteers with schizophrenia spectrum personality symptoms.

Authors aimed to evaluate the yield and effectiveness of recruiting community schizophrenia spectrum personality (SSP) subjects via targeted newspaper advertisements listing SSP traits. Eight newspaper advertisements listing SSP traits were placed in regional newspapers over a 3-year period. Respondents (n = 209) were screened thoroughly via telephone, and eligible subjects were invited for face-to-face clinical interviews. One hundred and one subjects (48% of the respondents) were screened out over the phone and another 30% were no-shows or refused. Of the 46 subjects who were interviewed, a majority (24 subjects; 52%) met this study's criteria for SSP. These subjects experienced significant psychotic-like symptoms, as ascertained by a self-rating scale, and showed a downward drift in their socio-economic status. One can successfully recruit SSP subjects, with high yield, using targeted telephone advertisements combined with thorough telephone screening.

Podocyte phenotypes as defined by expression and distribution of GLEPP1 in the developing glomerulus and in nephrotic glomeruli from MCD, CNF, and FSGS. A dedifferentiation hypothesis for the nephrotic syndrome.

Glomerular epithelial protein 1 (GLEPP1) is a podocyte receptor membrane protein tyrosine phosphatase located on the apical cell membrane of visceral glomerular epithelial cell (VGEC) foot processes. Double label immunofluorescence, immunoelectron microscopy, and peroxidase immunohistochemistry were used to map the GLEPP1 distribution in the developing glomerulus and in minimal-change nephropathy (MCN), congenital nephrotic syndrome of the Finnish type, and focal-segmental glomerulosclerosis (FSGS). In MCN GLEPP1 was shifted away from the glomerular basement membrane on the apical cell membrane of effaced foot processes. These data are compatible with the previously suggested concept that MCN can be considered a form of dedifferentiation of the podocyte phenotype. Similarly, changes seen in congenital nephrotic syndrome of the Finnish type can be considered a consequence of failure to complete normal podocyte development. In FSGS glomeruli GLEPP1 was frequently absent from VGECs, even when no sclerosis was detectable in that glomerulus. Therefore, in FSGS, VGECs may lose GLEPP1, and this loss appears to occur in the absence of scarring and may, therefore, precede the scarring process. We speculate that a changed VGEC phenotype that does not express GLEPP1 might have properties similar to the early undifferentiated VGEC developmental phenotype. GLEPP1 distribution pattern and absence from glomeruli of individuals with nephrotic syndrome may, therefore, represent a useful phenotypic marker.

Long-term low-dose cyclosporine therapy for severe psoriasis: effects on renal function and structure.

BACKGROUND: The effectiveness of cyclosporine in the treatment of severe psoriasis is well known. OBJECTIVE: We evaluated the efficacy and toxicity of systemic cyclosporine in patients with severe psoriasis, observing short-term (12 weeks) and long-term (3 to 5 years) effects. METHODS: To further elucidate efficacy and safety, 42 patients with severe psoriasis were treated initially with cyclosporine 5 to 6 mg/kg per day for 12 weeks. A subset of 14 patients continued maintenance treatment for 3.5 years to study the long-term effects of cyclosporine on renal function and structure. Renal biopsies were performed after 2.5 years and 3.5 years of treatment. Renal histologic findings were correlated with renal function. RESULTS: By weeks 8 and 12, 64% (n = 27) and 86% (n = 36) of patients, respectively, were rated clear or almost clear of the psoriasis. However, a subpopulation of 15 patients did not respond to 5 mg/kg daily but improved when the dose was increased to 6 mg/kg daily. Clearance or near clearance was achieved in 67% of this subpopulation after 4 weeks. For the 29 patients whose glomerular filtration rate (GFR) was measured, mean GFR fell by 7% from baseline to week 4 (p < 0.05). This change was reversible when dosage was reduced by 1 mg/kg per day in each of these patients. Patients older than 45 years of age experienced significant elevation of mean diastolic blood pressure and had reduced GFR and increased serum creatinine. After 2.5 years, of the 14 patients who continued maintenance treatment, two had biopsy specimens that showed moderate interstitial fibrosis and tubular atrophy. The remainder showed only minimal to mild structural damage. After 3.5 years of cyclosporine treatment, repeat renal biopsy specimens revealed slight increases in structural changes in nine subjects. These changes correlated with increasing age and drug-induced hypertension. CONCLUSION: We conclude that 5 mg/kg of cyclosporine daily is usually an effective initial dose for psoriasis. Patients who do not respond will often benefit from elevation of the dose to 6 mg/kg daily. Older patients experience cyclosporine-induced hypertension and changes in renal function and structure more frequently than do younger patients.

The role of cytokine networks in the local liver injury following hepatic ischemia/reperfusion in the rat.

The liver is highly susceptible to a number of pathological insults, including ischemia/reperfusion injury. We have previously employed an animal model of hepatic ischemia/reperfusion injury, and have shown that this injury induces the production and release of hepatic-derived tumor necrosis factor alpha (TNF-alpha), which mediates, in part, local liver injury following hepatic reperfusion. In the present study, we have extended these previous observations to assess whether an interrelationship exists between TNF-alpha and the neutrophil chemoattractant/activating factor, epithelial neutrophil activating protein, that may account for some of the pathology of neutrophil-mediated ischemia/reperfusion-induced liver injury. We observed that hepatic ischemia/reperfusion injury leads to: (1) a coincident increase in hepatic neutrophil sequestration, elevated serum alanine aminotransferase (ALT) levels, and hepatic production of epithelial neutrophil activating protein; (2) passive immunization with neutralizing antibodies to TNF-alpha resulted in significant suppression of hepatic-derived epithelial neutrophil activating protein; and (3) neutralization of epithelial neutrophil activating protein by passive immunization significantly attenuated neutrophil sequestration in the liver and serum ALT levels. These findings support the notion that local expression of hepatic epithelial neutrophil activating protein produced in response to TNF-alpha is an important mediator of the local neutrophil-dependent hepatic injury associated with hepatic ischemia/reperfusion.

The role of stem cell factor (c-kit ligand) and inflammatory cytokines in pulmonary mast cell activation.

Mast cells play a critical role in allergic airway responses via IgE-specific activation and release of potent inflammatory mediators. In the present study, we have isolated and characterized primary mast cell lines derived from the upper airways of normal mice. The primary mast cell lines were grown and maintained by incubation with interleukin-3 (IL-3) and stem cell factor (SCF) and shown to be c-kit (SCF receptor) positive by flow cytometry. Subsequently, we examined the proliferation of both airway and bone marrow derived mast cell lines in response to inflammatory and hematopoietic cytokines, including SCF, IL-1, IL-3, interferon-gamma, IL-4, and IL-10. The results from the pulmonary mast cell lines were compared with those from bone marrow derived mast cells. Pulmonary mast cell lines were capable of proliferating in response to IL-3, IL-4, IL-10, and SCF, whereas the combination of SCF with the other cytokines did not increase the response over SCF alone. In contrast, the bone marrow-derived mast cells proliferated strongest to SCF or IL-3, but only modestly to IL-4 and IL-10. Furthermore, the combination of SCF with IL-3, but not the other cytokines, exhibited an increase in bone marrow-derived mast cell proliferation. Cytokine-specific stimulation of histamine release in the airway-derived and bone marrow-derived mast cells showed parallel results. SCF was the only cytokine shown to induce substantial histamine release. However, when certain nonhistamine releasing cytokines were combined with SCF, a synergistic increase in histamine release was induced in upper airway, but not bone marrow-derived mast cells. The results of these studies suggest that cytokines differentially modulate induction of proliferation and degranulation of bone marrow and upper airway-derived mast cells and may further indicate a cytokine activational cascade in tissue mast cells.

Age-dependent injury in human umbilical vein endothelial cells: relationship to apoptosis and correlation with a lack of A20 expression.

BACKGROUND: It has recently been shown that human umbilical vein endothelial cells (HUVEC) become increasingly sensitive to growth factor deprivation, resulting in cell death, as a function of age in culture. The overall goal of the present study was to investigate the mechanism of lethal injury in these cells and compare the injury process to other known mechanisms of injury in the same cells. EXPERIMENTAL DESIGN: HUVEC were established in culture and maintained for four passages. Injury to first-passage cells and fourth-passage cells were examined for injury in the presence of agents that are known to confer resistance to apoptosis. Ultrastructural features of injury and DNA fragmentation patterns were assessed. Expression of factors that are known to be associated with resistance to apoptosis in other models were assessed. RESULTS: Fourth-passage HUVEC undergoing injury exhibited morphologic features characteristic of apoptosis and DNA fragmentation. Agents known to inhibit apoptotic cell injury in other models inhibited injury. A20 expression was correlated with resistance to injury in fourth-passage HUVEC, but there was no correlation between bcl-2 and bcl-x expression and resistance to injury. CONCLUSIONS: HUVEC injury resulting from growth factor deprivation increases as a function of age in vitro and appears to be a form of apoptosis. A20 expression may confer resistance to cell injury through this pathway.

Macrophage inflammatory protein-1 alpha mediates lung leukocyte recruitment, lung capillary leak, and early mortality in murine endotoxemia.

Systemic exposure to LPS initiates a complex sequence of events resulting in organ-specific leukocyte recruitment and end-organ injury. We hypothesized that macrophage inflammatory protein-1 alpha (MIP-1 alpha), a C-C chemokine with leukocyte chemotactic and activating properties, may play an important role in lung inflammatory cell recruitment, subsequent lung injury, and mortality in endotoxemia. CD-1 mice were challenged with LPS (200 micrograms), resulting in a maximal 3.5-fold increase in neutrophils (polymorphonuclear leukocytes (PMNs)) at 6 h post-LPS, and a 2.6-fold increase in numbers of macrophages (M phi) within lung minces at 24 h. A time-dependent increase in MIP-1 alpha mRNA and protein was detected in lung after LPS treatment, with immunolocalization of MIP-1 alpha to blood and lung M phi, and the subendothelium. The pretreatment of mice with rabbit anti-MIP-1 alpha Ab resulted in a decrease in the influx of PMNs at 6 h, and influx of M phi at 24 h post-LPS challenge, an approximately 65% reduction in LPS-induced lung permeability to Evans blue, and a modest decrease in mortality at 24, but not 48 h post-LPS. Furthermore, passive immunization of mice with anti-MIP-1 alpha serum resulted in a 35% reduction in ICAM-1 mRNA levels within lung homogenates post-LPS. Finally, the pretreatment of animals with sTNFR:Fc (soluble TNF receptor:Ig construct) resulted in a 60% reduction in LPS-induced MIP-1 alpha mRNA expression within lung homogenates at 4 h post-LPS. Our studies indicate that MIP-1 alpha plays an integral role as a mediator of both PMN and M phi recruitment in murine endotoxemia.

Bi-ventricular function assessed intraoperatively before and after anatomical correction of transposition of the great arteries.

After anatomical correction of transposition of the great arteries (TGA), the left ventricle (LV) is forced to develop systemic pressures without having had time for adaptation. Thus, one might expect dilatation of the LV at least in the very early intraoperative period following the operation. In nine patients with TGA aged 8-24 days (median 9.5 days) which were selected for arterial switch operation (ASO), Dacron-patch mounted thin piezoceramic transducers were attached intraoperatively by fibrin glue to opposite epicardial surfaces of the right (RV) and/or LV for continuous assessment of external minor diameters (RVD, LVD; sonomicrometry) before and after correction. Right and left ventricular pressures (RVP, LVP) were measured simultaneously and pressure-diameter loops were generated. Right and left ventricular power indices (RVPi, LVPi: = HRxVPxVsD) was calculated from heart rate, ventricular pressures, and systolic shortening of the respective ventricular diameter (RVsD, LVsD). Data obtained during circulatory steady-state immediately before extra-corporeal circulation (ECC) and up to 45 min after ECC were compared. By avoiding volume overload (CVP < or = 10 mmHg) at weaning off ECC and by lowering the systemic vascular resistance and, thus, LV afterload (approximately 8 micrograms.kg-1 min-1 dobutamine), the LV developed systemic pressure (70 +/- 7 vs. 41 +/- 4 mmHg) at unchanged diastolic LV end-diastolic pressure (LVedP) (10 +/- 3 mmHg). Left ventricular power index increased by 45 +/- 25%, although the extent of systolic shortening of LVD was reduced by 20 +/- 10%. Simultaneously, the RV was effectively unloaded (RVedP: 8 +/- 3 vs 11 +/- 6 mmHg; RVP: 39 +/- 7 vs 53 +/- 9 mmHg; RVPi: -42 +/- 27%).(ABSTRACT TRUNCATED AT 250 WORDS)

Central venous catheterization in infants and children with congenital heart diseases: experiences with 500 consecutive catheter placements.

In a prospective study results of central venous catheter (CVC) placements in a consecutive group of 500 patients with less than 20 kg body weight undergoing cardiac surgery were evaluated. The incidence of previous cardiac surgery was 21% and the incidence of factors preventing the primary puncture of the right jugular or innominate vein was 13.4%. The anesthesiologists were free to select the catheterization technique, site of puncture, and catheter type. All CVC insertions were performed prior to surgery under continuous circulatory monitoring and optimal positioning of the anesthetized patient. Ninety-six percent of all catheterizations were successful, 81% of them on the first attempt. In the 4% of cases where catheterization failed, a CVC had to be placed by the surgeon. Of all catheters, 66% were positioned via the right internal jugular (IJV) or innominate vein (IV), 8% via the left, 16% via an external jugular vein (EJV), and 5% via other veins. Seventy-six percent of CVC insertions were performed with the Seldinger technique. Of the four catheter types used in this study, double lumen catheters were most frequently selected (38%). Placement of 22-ga single lumen catheters was preferred in infants with less than 5 kg body weight, in spite of their tendency to kink. Observed complications (10% arterial puncture, 4% hematoma, and 1% intrathoracic bleeding) never required immediate surgical intervention. Careful selection of appropriate catheters, as well as extensive experience and knowledge of the anatomical structures involved in special heart defects, helped to keep the risk of complications low.

Experimental obliterative cholangitis. A model for the study of biliary atresia.

Noninfectious obliterative cholangitis results from biliary tract inflammation in clinical conditions such as biliary atresia and sclerosing cholangitis. The purpose of this study was to develop an animal model of noninfectious biliary tract inflammation and fibrosis. An implantable osmotic pump was connected to a catheter placed into the gallbladder of hamsters. Phorbol myristate acetate (PMA) was infused into the biliary tract for periods of 6 hours to 28 days. After 7 days the animals developed neutrophil infiltration, cellular necrosis, and edema of the biliary ducts. After 14 days, the animals demonstrated intrahepatic cholestasis with bile duct fibrosis and acute and chronic inflammatory cell infiltration. By 28 days pronounced portal fibrosis was present, some of which created an early bridging cirrhosis pattern. In addition there was evidence of neocholangiogenesis. We conclude that long-term PMA infusion into the biliary tract generates an inflammatory response characterized by obliterative cholangitis and fibrosis, sharing many of the histologic features of human biliary atresia. This model may provide a relatively simple technique for investigating the process of nonpyogenic biliary tract inflammation.

Injury of rat pulmonary alveolar epithelial cells by H2O2: dependence on phenotype and catalase.

In a variety of inflammatory lung diseases, type I alveolar epithelial cells are more likely to be injured than are type II cells. Because oxidants have been implicated as a cause of injury in various inflammatory lung diseases, we evaluated the effects of differentiation on alveolar epithelial cell susceptibility to H2O2-induced injury. With the use of isolated rat type II cells in culture, we found that the cytotoxic effect of H2O2 increased between days 2 and 7, when type II cells are known to lose their distinctive type II properties and assume a more type I-like appearance. We previously reported that type II cells utilized both intracellular catalase and glutathione-dependent reactions to protect against H2O2. We therefore examined whether alterations in either of these protective mechanisms were responsible for the differentiation-dependent changes in sensitivity to H2O2. We found that catalase activity within alveolar epithelial cells decreased between 2 and 7 days in culture, whereas no changes were detected in glutathione-dependent systems. We then used a histochemical technique that detects catalase activity and found that type II cells within rat lungs possessed numerous catalase-containing peroxisomes, whereas very few were detected in type I cells. These findings demonstrate that as type II cells assume a type I-like phenotype, they become more susceptible to H2O2-induced injury. This increased susceptibility is associated with reductions in intracellular catalase activity, both in vitro and in vivo.

Protection by glycine of proximal tubules from injury due to inhibitors of mitochondrial ATP production.

We have determined whether glycine or glutathione can protect rabbit proximal tubules damaged by chemical inhibitors of oxidative phosphorylation: antimycin A, rotenone, cyanide, oligomycin, or carbonyl cyanide m-chlorophenylhdrazone (CCCP). All the agents severely depleted cell ATP levels within 15 min and caused lethal cell injury, as quantified by lactate dehydrogenase (LDH) release. Glycine and glutathione largely prevented this injury without altering the primary effects of the inhibitors on tubule respiration or the depletion of ATP. Buthionine sulfoximine and 1,3-bis(2-chloroethyl)-1-nitrosourea decreased cell glutathione but did not prevent the protective effects of either glycine or glutathione in tubules treated with rotenone. Protection was sustained during both a 15-min exposure and a 45-min postwash period irrespective of whether the wash removed the agent or mitochondrial function recovered. Cysteine uniquely induced a dramatic recovery of mitochondrial function in tubules washed after treatment with CCCP. These data 1) demonstrate that the cytoprotective effects of glycine previously seen during hypoxia extend to other tubule lesions characterized by severe ATP depletion, 2) emphasize the actions of glycine to preserve cell structural integrity in spite of sustained severe impairment of ATP-generating processes in proximal tubules, and 3) indicate that it is glycine rather than intracellular or extracellular glutathione which mediates protection.

Ouabain-induced lethal proximal tubule cell injury is prevented by glycine.

Exposure to 1 mM ouabain for greater than 30 min caused lethal cell injury to isolated rabbit proximal tubules as measured by increased lactate dehydrogenase release. Addition of 2 mM glycine or glutathione to the incubation medium prevented this injury and a sharp fall of cell ATP that accompanied it. Glycine and glutathione did not alter rapid, early effects of ouabain to deplete cell K+ and inhibit respiration. Preservation of cellular glutathione was not required for protection. Glycine did not ameliorate ouabain-induced increases of cell water and did not prevent lethal cell injury associated with cell swelling produced by incubation in a high K+ concentration medium. In contrast, 100 mM mannitol, which at least partially ameliorated swelling in both ouabain and high-K+ medium, prevented lethal injury in high-K+ medium and decreased it in the presence of ouabain. The combination of glycine and mannitol completely prevented ouabain-induced lethal injury and cell water increases. These observations indicate that glycine, unlike mannitol, does not protect against primary volume-induced insults. Ouabain-induced lethal cell injury results from a process that includes both a volume component ameliorated by mannitol and a volume-independent component that is prevented by glycine and is closely associated with accelerated ATP depletion.

Tumor necrosis factor participates in the pathogenesis of acute immune complex alveolitis in the rat.

We have examined the role of intrapulmonary TNF in a rat model of acute immune complex-triggered alveolitis. Intratracheal instillation of IgG anti-bovine serum albumin (anti-BSA) followed by intravenous infusion of BSA results in acute alveolitis. Over the 4-h course of evolving lung injury, a 10-fold increase in TNF activity occurred in bronchoalveolar lavage (BAL) fluid. Immunohistochemical analysis of lung sections and BAL cells revealed that alveolar macrophages are the chief source of TNF. Antibodies that specifically neutralize rat TNF activity were raised in rabbits immunized with recombinant mouse TNF alpha. When administered into the lungs with anti-BSA, anti-TNF resulted in a marked reduction (up to 61%) in lung injury. Intratracheal instillation of exogenous TNF alone, or in combination with anti-BSA, resulted in an increase in lung injury compared to controls. Morphometric analysis and measurements of myeloperoxidase activities in whole lung extracts from rats treated with anti-TNF revealed a marked reduction in neutrophils compared to positive controls. The anti-TNF antibody preparation did not inhibit in vitro complement activation or diminish neutrophil chemotactic activity present in activated rat serum. These data indicate that intrapulmonary TNF activity is required for the full development of acute immune complex-triggered alveolitis, that alveolar macrophages are the primary source of this cytokine, and that TNF participates in the pathogenesis of immune complex alveolitis through a mechanism involving neutrophil recruitment.

Pancreatitis-induced acute lung injury. An ARDS model.

Cerulein-induced acute pancreatitis in rats is associated with acute lung injury characterized by increased pulmonary microvascular permeability, increased wet lung weights, and histologic features of alveolar capillary endothelial cell and pulmonary parenchymal injury. The alveolar capillary permeability index is increased 1.8-fold after a 3-hour injury (0.30 to 0.54, p less than 0.05). Gravimetric analysis shows a similar 1.5-fold increase in wet lung weights at 3 hours (0.35% vs. 0.51% of total body weight, p less than 0.05). Histologic features assessed by quantitative morphometric analysis include significant intra-alveolar hemorrhage (0.57 +/- 0.08 vs. 0.12 +/- 0.02 RBC/alveolus at 6 hours, p less than 0.001); endothelial cell disruption (28.11% vs. 4.3%, p less than 0.001); and marked, early neutrophil infiltration (7.45 +/- 0.53 vs. 0.83 +/- 0.18 PMN/hpf at 3 hours, p less than 0.001). The cerulein peptide itself, a cholecystokinin (CCK) analog, is naturally occurring and is not toxic and in several in vitro settings including exposure to pulmonary artery endothelial cells, Type II epithelial cells, and an ex vivo perfused lung preparation. The occurrence of this ARDS-like acute lung injury with acute pancreatitis provides an excellent experimental model to investigate mechanisms and mediators involved in the pathogenesis of ARDS.

Phagocytosis of Candida albicans enhances malignant behavior of murine tumor cells.

Murine tumor cells were induced to phagocytize either Candida albicans or group A streptococcal cells. The presence of microbial particles within the tumor cell cytoplasm had no effect on in vitro tumor cell growth. However, when Candida albicans-infected tumor cells were injected into syngeneic mice, they formed tumors that grew faster, invaded the surrounding normal tissue more rapidly and metastasized more rapidly than control tumor cells. Tumor cells infected with group A streptococcal particles did not grow faster or show increased malignant behavior. These data indicate that the in vivo behavior of malignant tumor cells can be modulated by microbial particles, which are often present in the microenvironment of the growing tumor.

Comparative O2-. responses of lung macrophages and blood phagocytic cells in the rat. Possible relevance to IgA immune complex induced lung injury.

IgA immune complex-induced lung injury in the rat is oxygen radical mediated and partially complement-dependent but develops fully after neutrophil depletion. The extent to which monocytes, lung interstitial macrophages, and alveolar macrophages may be involved in the development of lung injury in this model is unclear. To further understand the pathogenesis of IgA lung injury, we have examined the capacity of phagocytic cells isolated from different anatomic compartments of the lung to produce toxic oxygen-derived metabolites. [3H]Thymidine pulse labeling and autoradiography as well as in vivo phagocytosis studies were used to distinguish macrophages isolated from the alveolar and interstitial compartments. Lung interstitial macrophages were characterized ultrastructurally, cytochemically, and functionally. Interstitial macrophages were relatively uniform in size, had blunt pseudopodia, and contained almost no intracytoplasmic lamellar inclusions compared to alveolar macrophages. Similar to monocytes and alveolar macrophages, interstitial macrophages contained nonspecific esterase activity and exhibited the capacity to phagocytize latex and opsonized zymosan particles. Lung interstitial and alveolar macrophages incubated with IgA immune complexes, IgG immune complexes, or phorbol ester (PMA) produced similar amounts of O2-. in a dose-dependent manner. In contrast, peripheral blood neutrophils responded to IgG immune complexes and PMA but not to IgA immune complexes. Monocytes produced a small amount of O2-. in response to PMA but almost no O2-. in response to IgA or IgG immune complexes. These data are consistent with recent in vivo studies which indicate that IgA immune complex lung injury is neutrophil independent. The data provide direct in vitro evidence that lung interstitial and alveolar macrophages produce O2-. following incubation with PMA, IgA, or IgG immune complexes and may therefore contribute to the development of oxygen radical mediated lung injury.

Acute in vivo effects of human recombinant tumor necrosis factor.

Tumor necrosis factor is a peptide cytokine that induces hemorrhagic necrosis of some tumors and is responsible for the severe cachexia observed in advanced infectious diseases. We evaluated the acute effects of intravenous administration of purified human recombinant tumor necrosis factor in mice. With as little as 0.01 microgram/mouse (0.00045 mg/kg) a peripheral blood lymphopenia and neutrophilia developed as determined by flow cytometric analysis. At 1 microgram/mouse, the lymphopenia was both relative (21 +/- 3% versus 65 +/- 3%; p less than 0.001 treated versus control) and absolute (62 +/- 10 versus 229 +/- 29 X 10(4) cells/ml p less than 0.001). The neutrophilia was also relative (79 +/- 3% versus 34 +/- 3%; p less than 0.001 treated versus control) and absolute (237 +/- 26 versus 110 +/- 13 X 10(4) cell/ml; p less than 0.001). The neutrophilia was due to an increase in both mature and immature cells. At the higher doses the animals developed hypovolemic shock with an increased hematocrit and watery diarrhea occurred. Microscopic examination of the small bowel disclosed necrosis of the villi. Ultrastructural studies of the small bowel confirmed the necrosis and also showed severe endothelial cell damage, pyknotic nuclei, exocytosis of Paneth cell granules, and extravasation of red blood cells and neutrophils into the interstitium. A vascular leak syndrome developed with preferential fluid loss into the small and large bowel. These data demonstrate the potent in vivo effects of purified human recombinant tumor necrosis factor.