The Chediak-Higashi syndrome: microtubules in monocytes and lymphocytes

Recent investigations of Chediak-Higashi syndrome (CHS) leukocytes have suggested that defective cell function and formation of giant granules may be due to an inability of the cells to assemble microtubules because of an abnormality in synthesis of cyclic 3',5'-guanosine monophosphate (cGMP). In the present study we have examined normal and CHS lymphocytes and monocytes for the presence and frequency of centriole-associated microtubules. No statistically significant differences between the mean numbers of centriole associated microtubules in normal and CHS mononuclear cells could be detected. Results of the study fail to support the hypothesis that microtubule assembly is a fundamental defect in all CHS leukocytes.     

Impaired Microtubule Assembly and Polymorphonuclear Leucocyte Function in the Chediak-Higashi Syndrome Correctable by Ascorbic Acid

It was previously shown that the abnormal surface characteristics and defective bactericidal function of polymorphonuclear leucocytes (PMN) in the Chediak-Higashi syndrome (CHS) are correlated with impaired microtubule assembly, and in one patient direct electron microscopic evidence for an anomaly in microtubule assembly following surface membrane activation by concanavalin A (Con A). We show that very few microtubules are visible in CHS leucocytes from two additional patients under conditions where normal PMNs contain abundant microtubules, and that both in vivo and in vitro exposure of the CHS leucocytes to ascorbic acid promotes the assembly of microtubules. This agent, which normalizes chemotaxis and degranulation in CHS leucocytes, is shown also to correct granulocyte adherence in these leucocytes. It is suggested that the improved clinical course of patients with CHS following treatment with ascorbic acid is related at least in part to improvement of microtubule assembly and PMN function by the ascorbic acid.     

Role of microtubules in granulocyte adherence.

The adherence of human polymorphonuclear leukocytes (PMN) to nylon fibers is inhibited in a dose-dependent fashion by exposure in vitro of these cells to either colchicine or VM-26, both of which agents prevent microtubule assembly. Mean adherence of human PMN was 48% +/- 2%, following treatment with 10(-5) M colchicine or 10(-4) M VM-26 it was reduced to 31% +/- 2% and 7%, respectively. Peritoneal PMN obtained from mice and mink with Chediak-Higashi syndrome (CHS) thought to have a microtubule-membrane disorder affecting the PMN had a mean adherence of 29% +/- 3% and 40% +/- 8% compared to control values of 46% +/- 5% and 73% +/- 8%, respectively, from the mice and mink. Both ascorbic acid and bethanechol, shown previously to enhance microtubule assembly in humans with CHS, normalized granulocyte adherence in PMN obtained from mice with CHS. Cyclic nucleotide levels were not altered by treatment of human PMN with colchicine, nor did they differ between normal and CHS animals. Thus it appears that the state of microtubule assembly may directly affect the properties of the PMN plasma membrane without requiring alterations of cyclic nucleotides as an intermediary.     

Microtubules in the heart muscle of the postnatal and adult rat

In the postnatal rat heart, muscle cells continue to divide as well as increase in size. At the same time the cells in the soleus muscle (a slow skeletal muscle) do not divide, although they continue to grow in size. Since microtubules may have a role in orienting intracellular structures in muscle, we determined the numbers of microtubules/micron2 cross-sectional area in the rat heart papillary muscle during development. We have previously determined that in the soleus muscle, microtubule number/micron2 increases to a maximum at five to nine days of age, after which there is an abrupt decrease to a steady level characteristic of the adult [2]. The numbers of microtubules/micron2 in the heart were similar to those in the soleus muscle at the same age. The numbers of microtubules/micron2 increased from birth to a maximum at nine days, then decreased to a steady state. This decrease in microtubule number in heart muscle occurred at 9 to 11 days as in the soleus muscle. The distributions of microtubules are thus similar for cardiac and slow skeletal muscle, suggesting similar function(s) in these different muscle types.     

Abnormal distribution of complex carbohydrates in neutrophils of a patient with lactoferrin deficiency

Previous studies have identified patients with susceptibility to bacterial infection associated with lactoferrin deficiency in dysmorphic neutrophils containing abnormal or no secondary granules and abnormal nuclear segmentation. We have investigated the subcellular distribution of vicinal glycol-containing complex carbohydrates in marrow and blood myeloid cells of such a patient using the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) staining method and have examined the response of these neutrophils to the degranulating agents N-formylmethionyl-leucyl-phenylalanine (FMLP) and phorbol myristate acetate (PMA). As in normal specimens, immature primary granules were strongly PA-TCH-SP reactive; however, unlike normal specimens, masking of PA-TCH-SP reactivity did not occur in mature primary granules. Endoplasmic reticulum demonstrated moderately strong PA-TCH-SP staining, in contrast to absent staining of this organelle in normal promyelocytes and consistent with abnormal primary granule genesis. Small abnormal elongated granules (0.1-0.2 micron in diameter) were identified at the myelocyte state of development and were the predominant granule type in late neutrophils. These granules were identified as secondary granules on the basis of their PA-TCH-SP positivity and were differentiated from primary and tertiary granules on the basis of a lack of peroxidase, acid phosphatase, and sulfate staining. When the neutrophils were exposed to PMA, cell aggregation occurred, and the abnormal granules degranulated in a manner similar to the degranulation observed with normal secondary granules. Although PA- TCH-SP staining of the plasma membrane appeared normal, a decrease in FMLP receptors was demonstrated. Thus, a defect(s) is present in complex carbohydrate distribution and staining that involves primary and secondary granules and possibly the plasmalemma of neutrophils from this patient. This results in abnormal packaging of primary granules and synthesis of normal numbers of secondary granules that are qualitatively and morphologically abnormal, but can be recruited to degranulate with PMA.     

Abnormal peroxidase-positive granules in "specific granule" deficiency

"Specific granule" deficiency (SGD) has been previously associated with lactoferrin deficiency. The antimicrobial peptides termed defensins, comprising 30% of normal primary granule proteins, have also been shown to be markedly deficient in SGD. The present study was undertaken to correlate these findings with ultrastructural morphometric analysis and peroxidase cytochemistry. Peroxidase-positive, rim-stained, large, defensin-rich dense granules, previously described as a subpopulation of azurophil or primary granules in normal neutrophils, were markedly decreased in a patient with SGD. Morphometric studies of peroxidase- positive granules indicated an average peroxidase-positive granule area (all profiles) in the patient of 0.019 +/- 0.017 micron 2 (mean +/- SD, n = 941) compared to control values from normal neutrophils of two volunteers of 0.049 +/- 0.033 micron 2 (n = 896) and 0.050 +/- 0.039 micron 2 (n = 873) (P less than 0.001 between patient and control samples). Granule histograms showed a single peak of small peroxidase- positive granules, whereas control samples contained more prominent subpopulations of larger peroxidase-positive granules. The total number of peroxidase-positive granules per 100 micron 2 of cytoplasm in the patient was 255 +/- 124 (mean +/- SD, n = 15 cell profiles), which was similar to control values of 266 +/- 63 and 212 +/- 109. Thus, the defensin deficiency in SGD is associated with a decrease in size rather than number of peroxidase-positive granules; suggesting that defensins contribute to normal peroxidase-positive granule size and that SGD is a more global granule deficiency than originally thought.(ABSTRACT TRUNCATED AT 250 WORDS)     

Phorbol myristate acetate stimulates macrophage differentiation and replication and alters granulopoiesis and leukemogenesis in long-term bone marrow cultures

The effects of the tumor-promoter phorbol myristate acetate (PMA) on normal hemopoiesis and Friend leukemia virus (FLV) granulocytic leukemogenesis in long-term bone marrow cultures were examined. FLV- anemia-inducing strain (FLV-A) infected, Rauscher R-MuLV clone M52R infected, or uninfected control NIH Swiss mouse marrow cultures were treated weekly with PMA or 4-O-methyl-PMA at 2.0 ng/ml or 200.0 ng/ml. Addition of PMA to control uninfected or R-MuLV-infected cultures decreased production of nonadherent granulocytic cells and granulocyte- macrophage progenitor cells (GM-CFU-c), and increased the numbers of adherent macrophages. Addition of PMA to FLV-A-infected cultures did not inhibit generation of granulocytic leukemia cell lines even though the numbers of adherent adipocytes were decreased and adherent macrophages were increased. PMA treatment of freshly explanted whole bone marrow but not purified nonadherent GM-progenitor cells from long- term bone marrow cultures stimulated GM-CFU-c and cluster formation in the absence of added colony-stimulating factor (CSF). The sensitivity of purified GM-progenitor cells to L929 or WEHI-3 CSF was not altered by PMA; however, PMA treatment of bone marrow macrophages or peritoneal exudate macrophages stimulated detectable GM-CFU-c and cluster formation by purified GM-progenitor cells under conditions where equal numbers of untreated macrophages failed to be stimulatory. Thus, several PMA effects on hempoietic stem cells in vitro are mediated through indirect action on adherent stromal cells including macrophages.     

Neutrophil function in chronic neutrophilic leukemia: defective respiratory burst in response to phorbol esters.

Functional analyses were performed on neutrophils isolated from 6 patients from two institutions who displayed features of chronic neutrophilic leukemia (CNL). These neutrophils demonstrated a consistent deficiency (44 +/- 8% of control values) in superoxide anion (O2-) production in response to the phorbol ester, phorbol myristate acetate (PMA). O2- production in response to chemotactic peptides was near normal (82.3 +/- 10.7% of control values). Bacterial killing was normal in the two patients studied, and chemotaxis was diminished in response to zymosan-activated plasma and to high concentrations of chemotactic peptides in the patients studied. Cytosolic C kinase activity was decreased in one of the two patients studied. These results suggest that a deficient O2- release in response to PMA is a hallmark of neutrophils in CNL and may provide a diagnostic indicator of this condition.     

Electron microscopical studies on cutaneous leishmaniasis in Ethiopia. II. Parasite and host cell differences between the localized and the diffuse form

The ultrastructure of Leishmania aethiopica parasites and their host cells was investigated in lesions of 7 patients suffering from diffuse cutaneous leishmaniasis (DCL) and in lesions of 4 patients with localized cutaneous leishmaniasis (LCL). The appearance of host cells and parasites varied considerably in both disease forms. Host cell variations occurred especially in the number of cytoplasmic vesicles, the size of the parasitophorous vacuoles, and the number of amastigotes per parasitophorous vacuole. Differences concerned the occurrence of a special macrophage-type in DCL-lesions which was characterized by an electron-translucent cytoplasm and a low degree of parasitization, larger parasitophorous vacuoles with higher numbers of amastigotes per vacuole in infected macrophages from DCL-patients, and the number of electron dense granules in host cell vacuoles of DCL-patients. The parasites inducing DCL and LCL significantly differed in size and membrane structure: Amastigotes had a length of 2.27 +/- 0.48 micron and a width of 1.77 +/- 0.40 micron in DCL-lesions, and 1.92 +/- 0.40 micron and 1.48 +/- 0.32 micron in LCL-lesions. Promastigotes obtained from DCL-patients revealed 2078 +/- 308 integral membrane particles (IMP)/micron2 and 892 +/- 246 IMP/micron2 on the P- and E-fracture faces of plasma membranes, while the corresponding values of LCL-derived promastigotes amounted to 1690 +/- 376 IMP/micron2 and 652 +/- 274 IMP/micron2, respectively.     

The role of neutrophil membrane glycoprotein GP-150 in neutrophil adherence to endothelium in vitro

We have previously described two patients with a congenital defect in neutrophil function characterized by an inability to form pus. The patients' neutrophils lack a membrane glycoprotein of mol wt 150,000 daltons (GP-150) on analysis by SDS-PAGE. This glycoprotein is part of a membrane antigen complex recognized by the murine monoclonal antibody (MoAb) 60.3. Addition of MoAb 60.3 to normal neutrophils produces defects in chemotaxis and phagocytosis in vitro similar to those observed in the patients. Since neutrophil adherence to vascular endothelium is prerequisite to neutrophil emigration in vivo, we examined the interaction of the patients' neutrophils and normal neutrophils treated with MoAb 60.3 with cultured endothelium. Adherence was determined as the percentage of 51Cr-labeled purified peripheral blood neutrophils which remained adherent to plastic wells or endothelial monolayers after a 45-minute incubation at 37 degrees C. The percentage of neutrophils from patient 1 remaining adherent to uncoated, fibronectin-coated, or laminin-coated plastic was similar to that observed in normal neutrophils (55% to 84% adherence with normal neutrophils v 73% to 78% adherence with the patient's neutrophils and 63% to 82% adherence with MoAb 60.3-treated normal neutrophils). The adherence of the neutrophils from patient 1 and MoAb 60.3-treated normal neutrophils to human or bovine endothelium in serum-free medium was also not significantly different from that observed in normal neutrophils (less than 10% adherence with normal, MoAb 60.3-treated, and patient neutrophils). In medium containing 10% autologous or heterologous human plasma, however, the adherence of neutrophils from patient 1 or MoAb 60.3-treated normal neutrophils to endothelial monolayers was significantly reduced (35% +/- 7% of normal neutrophils in seven experiments). Although phorbol myristate acetate (PMA) (10 ng/mL) and calcium ionophore A23187 (10(-5) mol/L) markedly increased the adherence of normal neutrophils to endothelial monolayers in serum- free medium (40% to 85% adherence), neither agent increased the adherence of the neutrophils from patient 1 or normal neutrophils treated with MoAb 60.3 (less than 5% adherence). The adherence of PMA- activated neutrophils from patient 2 to endothelial monolayers was also markedly decreased when compared with that of normal neutrophils. Postsecretory cell-free supernatants from PMA-activated normal neutrophils failed to augment adherence of neutrophils from patient 1 (less than 5% adherence).(ABSTRACT TRUNCATED AT 400 WORDS)     

A Quantitative Assessment of Neutrophil Marrow in Seven Patients with Chronic Granulocytic Leukaemia

Neutrophil marrow cellularity was determined in seven patients with chronic granulocytic leukaemia (CGL). The size of the mitotic pool (promyelocytes and myelocytes) and the number of metamyelocytes and bands and of segmented neutrophils in the postmitotic pool were determined from measurements of neutrophil--erythroid ratios in marrow biopsy sections and ferrokinetic estimates of marrow normoblasts. A section mitotic index was calculated in each patient from the numbers of mitotic figures and mitotic pool cells counted on marrow sections. Basal values previously established in normal subjects for the mitotic pool, for metamyelocytes and bands, and for segmented neutrophils, were 2.11 +/- 0.36 x 10(9) cells/kg, 3.33 +/- 0.61 x 10(9) cells/kg, and 2.26 +/- 0.42 x 10(9) cells/kg, respectively (+/- 1 SD, n = 13). The basal section mitotic index was 0.07 +/- 0.01 (+/- 1 SD, n = 13). In the seven patients with CGL the mitotic pool comprised 3.71--25.70 x 10(9) cells/kg, metamyelocytes and bands 7.70--51.02 x 10(9) cells/kg, and segmented neutrophils 3.45--28.81 x 10(9) cells/kg. Mitotic indices ranged from 0.04 to 0.10. No relationship was found between marrow cellularity and blood neutrophil count. A negative correlation existed between mitotic pool cellularity and mitotic index (r = -0.76, n = 7 pairs). The results provide quantitative affirmation of neutrophil marrow hyperplasia and of increased neutrophil production by the marrow in CGL.     

ATP-dependent formation and motility of aster-like structures with isolated calf brain microtubule proteins.

Microtubule proteins isolated from calf brain will undergo gelation-contraction in the presence of ATP. We have now examined this process by video-enhanced contrast microscopy. After ATP addition to steady-state microtubules, slow (1-5 micron/min), linear movements of particles and microtubules toward aggregation centers occur. The resulting structures resemble mitotic spindle asters. During the time when gel contraction occurs, asters move (at 1-5 micron/min) toward other nearby asters. This is accompanied by the apparent shortening of the microtubules running between the asters. This is the first example of isolated microtubules undergoing a process that has similarities to half-spindle shortening during anaphase A. Formation of aster-like structures without preformed microtubule organizing centers raises the possibility that a similar process may contribute to microtubule organization in vivo.     

Changes in the structural and functional properties of human eosinophils during experimental hookworm infection

Normal volunteers were infected with hookworm larvae Necator americanus. Peripheral blood counts showed a mean of 524 +/- 29 eosinophils/mm3 of blood before infection and a mean of 3,008 +/- 456 eosinophils/mm3 of blood during infection (P less than .01). Absolute numbers of neutrophils did not change. Eosinophils and neutrophils from the infected period were compared with the noninfected state in each subject. The percentage of hypodense eosinophils increased from a mean of 34% +/- 13% to 80% +/- 7% during infection (P less than .05). Superoxide production of eosinophils increased from a mean of 56 +/- 9 to 97 +/- 12 nmol of O2-./10(6) cells per 60 min (P less than .05) during infection. Chemotaxis of eosinophils to Escherichia coli endotoxin-activated serum increased from a mean average distance migrated of 19 +/- 2 micron (P less than .05), whereas neutrophil responsiveness did not change. This is the first report of changes in eosinophil density and stimulation of eosinophil function in normal hosts experimentally infected with hookworm. The data indicate that hookworm infection preferentially increases eosinophil production and activity with little effect on neutrophils.     

Oxygen radical production by alveolar inflammatory cells in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic inflammatory interstitial lung disease characterized by the accumulation of alveolar macrophages (AMs) and neutrophils in the lower respiratory tract, parenchymal cell injury, and fibrosis of the alveolar structure. Reactive oxygen intermediates (ROI) are claimed to be a major cause of tissue damage in IPF; however, the source of ROI has not been unequivocally identified. AMs, as well as neutrophils, are capable of releasing these agents. The contributions of these possible sources are not known. To address this question, we evaluated the spontaneous and stimulated (PMA or zymosan) ROI release of total bronchoalveolar cells and isolated AMs in 14 patients with IPF by means of luminol-enhanced chemiluminescence. Bronchoalveolar lavage (BAL) cells from 17 individuals without any signs of inflammation served as controls. In comparison with the controls, the spontaneous as well as the stimulated ROI release of total BAL cells in IPF are markedly increased (20,763.9 +/- 5,079.3 versus 2,509.5 +/- 300.6 counts/10 s/2.10(5) cells, spontaneously, IPF versus control; 106,819.3 +/- 33,802.8 versus 8,919 +/- 1,357.9 PMA induced; 41,597.1 +/- 8,442.6 versus 6,223.8 +/- 1,025.1 zymosan induced, p less than 0.001). Measurement of the ROI release of purified AMs revealed that these cells produce the bulk part of ROI released by BAL cells (84%). In spite of the fact that, on a per cell basis, the ROI release of neutrophils is 1.7-fold of that of AMs, there is no correlation between the ROI production of total BAL cells and the percentage of neutrophils in BAL, demonstrating a minor role of these cells in the generation of the total ROI burden in IPF.(ABSTRACT TRUNCATED AT 250 WORDS)     

Microtubule curvatures under perpendicular electric forces reveal a low persistence length

The mechanics of microtubules, cylindrical protein filaments that constitute the cytoskeleton, have been well characterized on long length scales. Here, we investigate the persistence length of short (approximately 0.1 microm) ends of microtubules by measuring the trajectories of kinesin-propelled microtubules under perpendicular electric forces. We relate the measured trajectory curvatures to the biased thermal fluctuations of the leading microtubule end, and upon including all electrohydrodynamic forces, we find that the persistence length of the microtubule ends is only 0.08 +/- 0.02 mm. This is significantly shorter than the well established value of approximately 4-8 mm that is measured for long microtubules. Our data are in good agreement with recent theoretical predictions that microtubules mechanically behave as a loose assembly of independent protofilaments on these short length scales.     

Monocyte-induced inhibition of lymphocyte response to phytohaemagglutinin in progressive systemic sclerosis.

In patients with progressive systemic sclerosis (PSS) lymphocyte responses to phytohaemagglutinin (PHA) are abnormal (27.2 +/- 3.5 X 10(-3) counts per minute (cpm) versus 69.8 +/- 4.4 X 10(-3) for normal persons, p less than 0.005). Removal of adherent peripheral blood mononuclear cells improves the response of PSS lymphocytes (42.3 +/- 3.4 X 10(-3) cpm, 155% of control) but diminishes the response of normal lymphocytes (60.3 +/- 5.9 +/- 10(-3), 86% of control). Supernatant fluids from cultures of PSS unfractionated and adherent cells depress normal T cell response to PHA (64% and 55% of control respectively), but supernatant fluids from normal unfractionated and adherent cells do not (104% and 101% of control). Supernatant fluids of PSS and normal adherent cells, cultured in the presence of indomethacin, are not inhibitory to normal T cells (109 +/- 15% and 124 +/- 14% of control respectively). Supernatant fluids from PSS patients are more inhibitory than comparable fluids from patients with systemic lupus erythematosus (60 +/- 8% of control versus 80 +/- 5% of control). These data support the hypothesis that cellular immunity is abnormal in patients with PSS and indicate that adherent mononuclear cells mediate at least one component of the abnormality via an indomethacin-sensitive mechanism.     

Differentiation of cellular processes involved in the induction and maintenance of stimulated neutrophil adherence

Neutrophil adherence stimulated by phorbol myristate acetate (PMA) was investigated by quantitating the attachment of 51Cr-labeled neutrophils to plastic surfaces and to the endothelium of umbilical veins mounted in compartmentalized Lucite chambers. PMA-induced adherence could be functionally separated into an induction phase requiring cellular metabolism and a Mg++ dependent maintenance phase that was independent of cellular metabolism. Thus, metabolic inhibitors (N-ethylmaleimide, 2- deoxyglucose) blocked adherence when added to neutrophils prior to PMA, but did not cause detachment of cells adhering as a consequence of prior exposure to PMA. PMA failed to induce adherence of neutrophils incubated at low (0.4 degree C) temperature, but temperature reduction, even for prolonged periods, did not cause detachment of adherent cells. Thus, the attractive forces that mediate stimulated adherence persist independently of any sustained metabolic response to the inducing stimulus. However, removal of Mg++ from the media above adherent cells resulted in immediate detachment, indicating that the cation was required for the persistent expression or maintenance of the attractive forces involved. The extent of stimulated adherence correlated well with the extent of degranulation when rates were varied by limiting the incubation time or stimulus concentration. This correlation was not absolute; in the absence of Mg++, PMA induced degranulation normally but failed to enhance adherence. To explain these findings, we investigated the possibility that PMA-stimulated adherence was maintained by Mg++-dependent cellular adherence molecules released during exocytosis. Supernatants of stimulated neutrophils were devoid of adherence-promoting activity, and only weak activity was recovered in supernatants of mechanically disrupted neutrophils. PMA effectively stimulated the tight adherence of degranulated neutrophil cytoplasts to plastic surfaces and did so in the absence of stimulated granule enzyme release. Thus, conditions have been identified under which degranulation occurs in the absence of adherence (removal of Mg++) and adherence occurs without concurrent degranulation. Since neutrophil cytoplasts do contain some granule products and granule material can be identified on cytoplast membranes, it is possible that degranulation or granule products may be involved in the adherent response. However, hyperadherence was shown to develop in the absence of de novo degranulation.(ABSTRACT TRUNCATED AT 400 WORDS)     

Cardiocyte cytoskeleton in patients with left ventricular pressure overload hypertrophy

OBJECTIVES: We sought to determine whether the cardiocyte microtubule network densification characteristic of animal models of severe pressure overload cardiac hypertrophy occurs in human patients. BACKGROUND: In animal models of clinical entities causative of severe right and left ventricular (LV) pressure overload hypertrophy, increased density of the cellular microtubule network, through viscous loading of active myofilaments, causes contractile dysfunction that is normalized by microtubule depolymerization. These linked contractile and cytoskeletal abnormalities, based on augmented tubulin synthesis and microtubule stability, progress during the transition to heart failure. METHODS: Thirteen patients with symptomatic aortic stenosis (AS) (aortic valve area = 0.6 +/- 0.1 cm2) and two control patients without AS were studied. No patient had aortic insufficiency, significant coronary artery disease or abnormal segmental LV wall motion. Left ventricular function was assessed by echocardiography and cardiac catheterization before aortic valve replacement. Left ventricular biopsies obtained at surgery before cardioplegia were separated into free and polymerized tubulin fractions before analysis. Midwall LV fractional shortening versus mean LV wall stress in the AS patients was compared with that in 84 normal patients. RESULTS: Four AS patients had normal LV function and microtubule protein concentration; six had decreased LV function and increased microtubule protein concentration, and three had borderline LV function and microtubule protein concentration, such that there was an inverse relationship of midwall LV fractional shortening to microtubule protein. CONCLUSIONS: In patients, as in animal models of severe LV pressure overload hypertrophy, myocardial dysfunction is associated with increased microtubules, suggesting that this may be one mechanism contributing to the development of congestive heart failure in patients with AS.     

Superoxide anion release from blood and bone marrow neutrophils is altered by endotoxemia

In vivo endotoxin infusion produces neutrophil-mediated acute lung injury and increases superoxide anion release from phorbol myristate acetate (PMA)-stimulated blood neutrophils collected 18-24 hours after the infusion. Because the turnover time of circulating blood neutrophils is only 6-8 hours, it was hypothesized that the prolonged increase in superoxide anion release from peripheral blood neutrophils is associated with increased superoxide anion release from bone marrow neutrophils. To test this hypothesis, two doses of Escherichia coli endotoxin (5.0 and 0.5 micrograms/kg) were infused into chronically instrumented awake sheep. Blood and bone marrow neutrophils were collected 24 hours after the infusion, and superoxide anion release from unstimulated and PMA-stimulated neutrophils was measured in vitro. Endotoxin infusion produced an increase in pulmonary microvascular permeability, in intravascular activation (degranulation) of blood neutrophils, and in circulating blood neutrophils 24 hours after the infusion. High-dose endotoxin (5.0 micrograms/kg; n = 4) increased superoxide anion release from unstimulated peripheral blood neutrophils (2.25 +/- 0.38 times baseline [p less than or equal to 0.05]) and from peripheral blood neutrophils stimulated with 10(-9) M PMA in vitro (1.46 +/- 0.55 times baseline). Low-dose endotoxin (0.5 micrograms/kg; n = 5), on the other hand, did not alter superoxide anion release from peripheral blood neutrophils. Bone marrow neutrophils could not be isolated reproducibly after high-dose endotoxin because of leukoaggregation. Bone marrow neutrophils were isolated after low-dose endotoxin infusion. Stimulation of these cells with 10(-9) M PMA in vitro resulted in a two- to fourfold increase above control release (p less than or equal to 0.05). Increased superoxide anion release from both peripheral blood and bone marrow neutrophils occurred in the absence of circulating endotoxin, as measured by a Limulus assay. These results show that the prolonged increase in superoxide anion release from peripheral blood neutrophils is associated with an increase in the superoxide anion release from bone marrow neutrophils. Furthermore, the recruitment of affected bone marrow neutrophils into peripheral blood may explain the increased superoxide anion release from blood neutrophils 24 hours after endotoxin infusion.     

Alveolar macrophages from patients with asbestos exposure release increased levels of leukotriene B4

The alveolar influx and subsequent activation of inflammatory cells such as neutrophils and eosinophils are believed to be important in the pathogenesis of many interstitial lung disorders, including asbestosis. Indices of lower respiratory tract abnormalities detected by bronchoalveolar lavage (BAL) were investigated in 93 asbestos-exposed workers as well as in smoking (n = 12) and nonsmoking (n = 10) control subjects. Patients with clinical asbestosis (n = 12) exhibited increases in both BAL neutrophils and BAL eosinophils, expressed as both percentage of total cells and total numbers, when compared to asbestos-exposed workers without asbestosis (n = 81) and control subjects. Significantly greater numbers of BAL neutrophils were also found in asbestos-exposed workers without asbestosis than in either smoking or nonsmoking control subjects. These abnormalities correlated significantly with in vitro BAL alveolar macrophage production of the potent leukocyte chemotaxin, leukotriene B4 (LTB4). For example, basal, unstimulated LTB4 production was 3.1 +/- 0.8 ng/10(6) alveolar macrophages for patients with asbestosis, 1.05 +/- 0.2 ng/10(6) cells in asbestos workers without asbestosis, 0.9 +/- 0.2 ng/10(6) cells in control nonsmokers, and 0.2 +/- 0.05 ng/10(6) cells in control smokers. Stimulated LTB4 release from BAL alveolar macrophages (A23187 or arachidonate) was even more pronounced in asbestos workers with or without asbestosis, suggesting an in vivo priming effect on alveolar macrophage synthesis of LTB4. Cell-free BAL supernatants from asbestos-exposed patients with or without asbestosis also contained significantly greater amounts of LTB4 than did those from control subjects, indicating enhanced in vivo production of this inflammatory mediator.(ABSTRACT TRUNCATED AT 250 WORDS)