Polymorphonuclear Phagocytes Research Articles

Neutrophils in Intestinal Inflammation: What We Know and What We Could Expect for the Near Future

Neutrophils are short-lived cells that play a crucial role in inflammation. As in other tissues, these polymorphonuclear phagocytes are involved in the intestinal inflammatory response, on the one hand, contributing to the activation and recruitment of other immune cells, but on the other hand, facilitating intestinal mucosa repair by releasing mediators that aid in the resolution of inflammation. Even though these responses are helpful in physiological conditions, excessive recruitment of activated neutrophils in the gut correlates with increased mucosal damage and severe symptoms in patients with inflammatory bowel disease (IBD) and pre-clinical models of colitis. Thus, there is growing interest in controlling their biology to generate novel therapeutic approaches capable of reducing exacerbated intestinal inflammation. However, the beneficial and harmful effects of neutrophils on intestinal inflammation are still controversial. With this review, we summarise and discuss the most updated literature showing how neutrophils (and neutrophil extracellular traps) contribute to developing and resolving intestinal inflammation and their putative use as therapeutic targets.

Study to determine the effectiveness of dietary supplementation in pediatric patients with nutritional and health concerns

Aim: The study's main objective was to see whether the well-known probiotic Bifidobacterium lactis might aid in the development of children. Method: A nine-week clinical study involving 400 children aged between 5 to 10 years, was conducted to evaluate the efficacy of food supplementation. Stage 1 participants took 150 ml of low-fat milk twice a day for three weeks as a baseline diet control. Probiotics (Bifidobacterium lactis) were added to milk during stage 2 in a usual dosage (4×1010 organisms /d) or a low dose (4×109 organisms /d) for 3 weeks. During stage 3, for three weeks, they took low-fat milk. Peripheral blood samples were used to examine changes in the ratios of tumor-cell-killing and leukocyte phagocytic activities. Result: The level of NK cells and T lymphocytes were found to be increased in the blood of the individuals. NK cell’s tumoricidal activity was also increased following B. lactis intake, as were the phagocytic capacities of mononuclear and polymorphonuclear phagocytes. Subjects with weak pretreatment immune responses had the highest improvement in immunity. Conclusion: Supplementing the diets of children with B. lactis (a probiotic) may help improve their cellular immunity and physical development.

Monocytes, macrophages, dendritic cells and neutrophils: an update on lifespan kinetics in health and disease

Phagocytes form a family of immune cells that play a crucial role in tissue maintenance and help orchestrate the immune response. This family of cells can be separated by their nuclear morphology into mononuclear and polymorphonuclear phagocytes. The generation of these cells in the bone marrow, to the blood and finally into tissues is a tightly regulated process. Ensuring the adequate production of these cells and their timely removal is key for both the initiation and resolution of inflammation. Insight into the kinetic profiles of innate myeloid cells during steady state and pathology will permit the rational development of therapies to boost the production of these cells in times of need or reduce them when detrimental.

Mononuclear but Not Polymorphonuclear Phagocyte Depletion Increases Circulation Times and Improves Mammary Tumor-Homing Efficiency of Donor Bone Marrow-Derived Monocytes.

Tumor associated macrophages are an essential part of the tumor microenvironment. Consequently, bone marrow-derived monocytes (BMDMs) are continuously recruited to tumors and are therefore seen as ideal delivery vehicles with tumor-targeting properties. By using immune cell depleting agents and macroscopic in vivo fluorescence imaging, we demonstrated that removal of endogenous monocytes and macrophages (but not neutrophils) leads to an increased tumor accumulation of exogenously administered BMDMs. By means of intravital microscopy (IVM), we confirmed our macroscopic findings on a cellular level and visualized in real time the migration of the donor BMDMs in the tumors of living animals. Moreover, IVM also revealed that clodronate-mediated depletion drastically increases the circulation time of the exogenously administered BMDMs. In summary, these new insights illustrate that impairment of the mononuclear phagocyte system increases the circulation time and tumor accumulation of donor BMDMs.

Вплив улінастатину на метаболізм циркулюючих лейкоцитів та сироватковий рівень негістонових білків 1 високомобільної групи у хворих з гострим панкреатитом

Мета. Дослідити вплив лікування хворих з гострим панкреатитом (ГП) з використанням препарату улінастатин (УС) на функціональний стан циркулюючих лейкоцитів та сироватковий рівень негістонових білків 1 високомобільної групи (High Mobility Group Box 1 protein - HMGB1).
 Матеріали і методи. У дослідження включено 60 хворих з ГП, яких лікували у хірургічному відділенні №2 Київської міської клінічної лікарні швидкої медичної допомоги. Про стан метаболізму циркулюючих фагоцитів судили за показниками продукції реактивних форм кисню (РФК) та фагоцитарною активністю, які визначали методом проточної цитометрії. Для визначення сироваткового рівня HMGB1 застосовували метод імуноферментного аналізу.
 Результати. Про позитивний терапевтичний ефект УС свідчили зниження синтезу РФК циркулюючими лейкоцитами (в середньому у 2 рази), помірне посилення фагоцитарної активності циркулюючих моно- та поліморфноядерних фагоцитів, зниження сироваткового рівня HMGB1 на 27%.
 Висновки. Включення до складу лікувального алгоритму УС посилює протизапальний та антиоксидантний ефекти лікування хворих з ГП.

A Critical Role for HlgA in Staphylococcus aureus Pathogenesis Revealed by A Switch in the SaeRS Two-Component Regulatory System.

Cytolytic pore-forming toxins including alpha hemolysin (Hla) and bicomponent leukotoxins play an important role in the pathogenesis of Staphylococcus aureus. These toxins kill the polymorphonuclear phagocytes (PMNs), disrupt epithelial and endothelial barriers, and lyse erythrocytes to provide iron for bacterial growth. The expression of these toxins is regulated by the two-component sensing systems Sae and Agr. Here, we report that a point mutation (L18P) in SaeS, the histidine kinase sensor of the Sae system, renders the S. aureus Newman hemolytic activity fully independent of Hla and drastically increases the PMN lytic activity. Furthermore, this Hla-independent activity, unlike Hla itself, can lyse human erythrocytes. The Hla-independent activity towards human erythrocytes was also evident in USA300, however, under strict agr control. Gene knockout studies revealed that this Hla-independent Sae-regulated activity was entirely dependent on gamma hemolysin A subunit (HlgA). In contrast, hemolytic activity of Newman towards human erythrocytes from HlgAB resistant donors was completely dependent on agr. The culture supernatant from Newman S. aureus could be neutralized by antisera against two vaccine candidates based on LukS and LukF subunits of Panton-Valentine leukocidin but not by an anti-Hla neutralizing antibody. These findings display the complex involvement of Sae and Agr systems in regulating the virulence of S. aureus and have important implications for vaccine and immunotherapeutics development for S. aureus disease in humans.

ФУНКЦІОНАЛЬНІ ХАРАКТЕРИСТИКИ ЦИРКУЛЮЮЧИХ ФАГОЦИТІВ ЩУРІВ ІЗ ГЛІОМОЮ С6

Gliomas, tumors of the central nervous system, are a heterogeneous group of neoplasms of neuroectodermal origin. Gliomas are the most common primary brain tumors and cmprise about 80% of all malignant neoplasms of this location. The growth of malignant glioma is accompanied by the development of local and systemic immunosuppression that is a distinctive characteristics of the disease. At the early stages of tumor growth, glioma cells secrete numerous chemokines, cytokines and other biologically active mediators that contribute to the infiltration of tumor tissue by immune cells: resident microglial cells, as well as monocytes, granulocytes, T-cells, B-cells etc. Tumor-associated phagocytes comprise most significant part of the immunocytes in the microenvironment of malignant gliomas. These cells play a leading role in the development of local immunosuppression. The triggers of systemic immunosuppression, as well as the relationship between local and systemic immunosuppression is virtually unexplored and requires an in-depth study of the functional characteristics of circulating cells of the immune system. The aim of this work was to determine the phenotypic and functional characteristics of circulating phagocytes in rats with C6 glioma. Metabolic and phenotypic indices of circulating phagocytes were examined at different time point of tumor growth. It has been established that the late stages of C6 glioma growth in rats are associated with changes in the functional characteristics of peripheral blood mono- and polymorphonuclear phagocytes: a decrease in oxidative metabolism, an increase in phagocytic activity along with an increase CD206 expression. Taken together these alteration are characteristic for alternatively activated phagocytes that can participate in the development of glioma-associated systemic immunosupression. Keywords.

Activation and IL-1β secretion of human peripheral phagocytes infected with Actinomadura madurae, Nocardia asteroides and Candida albicans.

To evaluate the ability of Actinomadura madurae (A.madurae) and Nocardia asteroides (N.asteroides), using Candida albicans (C.albicans) as prototypic control, to elicit the activation and IL-1β secretion of blood phagocytic cells from healthy donors. Microscopic evaluation of phagocytosis/activation, cell viability and spectrophotometric quantitation of endocytosis/activation, were assessed by using formazan blue test in human blood phagocytes infected with C.albicans, A. madurae or N. asteroides treated with either normal human serum (NHS) or with decomplemented NHS. Interlukin-1β from culture supernatants of infected polymorphonuclear was tested by ELISA kit assay. Microscopic assay showed that phagocytosis and activation of adherent mononuclear phagocytes were greater with C. albicans followed by A. madurae and then by N. asteroides. Spectrophotometric assay in polymorphonuclear phagocytes infected with NHS-treated pathogens indicated that activation was similarly higher by C.albicans and A.madurae and lower by N. asteroides. Kinetic assays in infected polymorphonuclear cells showed that viability was decreased by C. albicans and N. asteroides or unaffected with A. madurae. Levels of IL-1β at 8h of incubation were higher with C. albicans followed by A. madurae whereas lower levels were found with N. asteroides. The extent of cell-viability and activation as well IL-1β secretion may be related with the virulence of C. albicans and N. asteroides and other parameters remain to be explored for assessing the virulence of A. madurae.

Human neutrophil peptide-1 decreases during ageing in selected Mexican population.

Antimicrobial peptide innate immunity plays a central role in the susceptibility to infectious diseases, as has been described extensively in different settings. However, the role that these molecules play in the immunity mediated by polymorphonuclear phagocytes as part of the innate immunity of ageing individuals has not been described. In the present study, we addressed the question whether antimicrobial activity in polymorphonuclear cells from elderly individuals was altered in comparison with young adults. We compared phagocytosis index, bacterial killing efficiency, myeloperoxidase activity and cathelicidin expression. Results showed that there were no statistical differences among groups. However, human neutrophil peptide-1 (HNP-1) was decreased in the elderly individuals group. Results suggest that the decreased HNP-1 production in the polymorphonuclear phagocytes form elderly individuals might have an important participation in the increased susceptibility to infectious diseases.

Neutrophils: The Role of Oxidative and Nitrosative Stress in Health and Disease.

Neutrophils constitute the first line of the innate immunity in humans. They employ several strategies to trap and kill microorganisms, such as phagocytosis, degranulation, and the formation of extracellular traps (NETs). It has been well documented, that generation of reactive oxygen and nitrogen species (ROS and RNS) is crucial in the life cycle of a polymorphonuclear phagocyte. These compounds due to high reactivity act as powerful antimicrobial factors in the process of pathogens clearance and can also modulate immunological response. On the other hand, excessive amount of free radicals may have detrimental effect on host tissues and markers of oxidative and nitrosative stress are detectable in many diseases. It is necessary to maintain the balance between ROS/RNS formation and removal. The review highlights our current understanding of the role of ROS and RNS produced by neutrophils in health and disease.

Gene Expression of Formyl Peptide Receptor 1 in Eosinophils of Iraqi Patients with Extrinsic Allergic Asthma

The formyl peptide receptor 1 (FPR1) is a member of the seven transmembrane G-protein coupled receptors family, mainly expressed by polymorphonuclear and mononuclear phagocytes and play a role in chemotaxis, killing of microorganisms through phagocytosis, and plays a important role players in innate immunity and host defense. The expression of (FPR1) in eosinophils has been investigated intensively with many diseases. In this study we explain regulation of (FPR1) expression in eosinophils during allergic disease such as (extrinsic Asthma). The study were conducted by using Reverse Transcription Real-Time PCR technique, and the fold changes of (FPR1) were estimated in the house dust mite (HDM) hypersensitive asthmatic patients group and birch pollen hypersensitive asthmatic patients group as well as healthy control group. The results show that there are high significant increase fold changes of (FPR1) expression (up regulation) in eosinophils of HDM hypersensitive asthmatic patients group. In contrast, birch pollen hypersensitive asthmatic patients group have no significant increase in FPR1 expression when compared with healthy control group. In conclusion, we concluded that formyl peptide receptor 1 (FPR1) that expressed by eosinophils have potential role in immune regulation and allergic diseases mainly extrinsic asthma when patients exposed to exogenous aggressive factor such as house dust mite.

Release of hydrogen peroxide by phagocytes from bovine colostrum in the peripartum period

Changes in the composition of colostrum in the peripartum period focused on the neonate’s immunity can minimize the response of the mammary gland before natural exposure to mastitis pathogens. This research evaluated the oxidative activity of mononuclear and polymorphonuclear phagocytes of bovine colostrum. Bacteriologically negative (n = 171) bovine colostrum samples of first and second milking postpartum were evaluated. The oxidative activity was assessed by the production of hydrogen peroxide (H2O2) released either spontaneously or upon stimulation by enterotoxigenic Escherichia coli (ETEC). For this, three treatments were used: control (C) – only cells; non-opsonized (NO) - cells and ETEC non-opsonized; and opsonized (O) – cells and ETEC opsonized. Median values of concentrations (nmol/106) of H2O2 produced by cells obtained from the first and second milking treatments C, NO and O were 149.1 and 39.9 (P = 0.0007); 125.5 and 49.1 (P = 0.0007); 102.4 and 54.4 (P = 0.008), respectively. No differences were observed between the treatments at each milking. The amount of H2O2 produced at first milking exceeded the values found thereafter. Furthermore, the presence of bacteria did not determine the increased amount of H2O2 released by phagocytes. Thus, we concluded that the mammary gland’s events during the peripartum period have an effect on the proportion and activity of phagocytes, which can cause injuries to the breast parenchyma by the large amount of free radicals produced. The high frequency of bovine mastitis during this period indicates the need for studies of the immunity of the mammary gland and research of susceptibility factors for bacterial infections.

Human colostrum melatonin exhibits a day-night variation and modulates the activity of colostral phagocytes

Some studies report that hormone melatonin can be found in human milk, but the daily variation in colostrum melatonin is not available. This study verified the effects of milk collection time (diurnal/nocturnal) on colostral melatonin levels and the ability of this hormone to modulate colostral phagocyte activity. Colostrum samples were collected from 30 mothers during the day and night, for a total of 60 samples. We determined melatonin levels in colostrum and superoxide release and bacterial killing by colostral phagocytes. Melatonin levels were higher in colostrum samples collected at night. Phagocytes in nocturnal colostrum samples increased spontaneous superoxide release. In diurnal colostrum samples, mononuclear (MN) phagocytes increased superoxide release when exposed to enteropathogenic Escherichia coli (EPEC), but not polymorphonuclear (PMN) phagocytes. Phagocytes exposed to both EPEC and melatonin had higher superoxide release, independent of phagocyte type and colostrum collection period. Phagocytosis rate was higher in colostrum samples collected at night. In diurnal samples, EPEC killing by MN phagocytes was lower than by PMN phagocytes. Phagocytosis increased significantly in the presence of melatonin in both MN and PMN cells, irrespective of colostrum collection period. In response to melatonin, MN phagocytes from both diurnal and nocturnal samples increased bactericidal activity, whereas colostral PMN phagocytes increased it only in diurnal samples. The melatonin increased in the intracellular Ca2+ levels. The highest intracellular Ca2+ release were found in MN phagocytes diurnal samples. These results confirm that melatonin levels in human colostrum follow a day-night variation and increase phagocytic activity of colostral cells against bacteria.

Modulation of Human Colostrum Phagocyte Activity by the Glycine‐Adsorbed Polyethylene Glycol Microspheres

Colostrum is a secretion that contains immunologically active components, including immunocompetent cells and glycine, which has anti‐inflammatory, immunomodulatory, and cytoprotective effects. The aim of this study was to evaluate the adsorption of glycine onto polyethylene glycol (PEG) microspheres and to verify the immunomodulatory effect of this nanomaterial on human colostrum phagocytes. The PEG microspheres were evaluated by fluorescence microscopy. The effects of PEG microspheres with adsorbed glycine on viability, superoxide release, phagocytosis, microbicidal activity, and intracellular calcium release of mononuclear (MN) and polymorphonuclear (PMN) colostrum phagocytes were determined. Fluorescence microscopy analyses revealed that glycine was able to be adsorbed to the PEG microspheres. The PMN phagocytes exposed to glycine‐PEG microspheres showed the highest superoxide levels. The phagocytes (both MN and PMN) displayed increased microbicidal activity and intracellular calcium release in the presence of PEG microspheres with adsorbed glycine. These data suggest that the adsorption of PEG microspheres with adsorbed glycine was able to stimulate the colostrum phagocytes. This material may represent a possible alternative therapy for future clinical applications on patients with gastrointestinal infections.

Influence of VicRK and CovR on the interactions of Streptococcus mutans with phagocytes

Streptococcus mutans are members of the oral microbiota that are implicated in dental caries and infective endocarditis. To adapt to environmental stresses encountered during host colonization, these bacteria employ two-component regulatory systems, which modulate global changes in gene expression. These include the systems VicRK and CovR. In this study, we investigate the influence of VicRK and CovR in S. mutans interactions with mononuclear and polymorphonuclear (PMN) phagocytes. Patterns of S. mutans uptake by murine macrophages were determined in strains, which differ in the production of proteins regulated by VicRK and CovR. Bacterial uptake by murine macrophages and by PMN in human blood was analyzed in vicK and covR knockout mutants obtained in strains UA159 and LT11. Inactivation of covR did not affect uptake by macrophages, while vicK inactivation transiently reduced uptake only in LT11 (P < 0.05). In the two strains, inactivation of vicK and covR impaired uptake by PMN for a period of 1 h or more (P < 0.01-0.05). Mutant complementation with vicK or covR restored the PMN uptake phenotypes. This study indicates that VicRK and CovR regulate functions that influence bacterial susceptibility to phagocytosis, suggesting a novel role for these systems in the virulence of S. mutans.

Fluctuation in the Functional Activity of Human Colostrum Phagocytes to Streptococcus pneumoniae and Enteropathogenic Escherichia coli

Colostrum was shown to protect children against gastrointestinal and respiratory infections and to exhibit chronobiological variations in cellular and soluble components. However, circadian variations in the activity of these colostral elements are only partially understood. This study compared colostrum samples collected in the diurnal and nocturnal periods by assessing phagocytic activity against enteropathogenic Escherichia coli (EPEC) and Streptococcus pneumoniae (S. pneumoniae) as well as the role of colostral cells and soluble elements. Colostrum samples were collected from 30 mothers during both day and night. Superoxide anion release, phagocytosis and bactericidal activity by colostral mononuclear (MN) and polymorphonuclear (PMN) phagocytes in the presence of EPEC or S. pneumoniae were determined. Colostrum samples collected in the diurnal period had higher superoxide release in opsonized than in non-opsonized EPEC and S. pneumoniae, whereas in nocturnal samples it was increased in PMN phagocytes incubated with serum-opsonized S. pneumoniae. MN and PMN phagocytes in colostrum collected in both periods exhibited phagocytic activity for the bacteria tested. The highest EPEC killing by MN phagocytes was observed in samples collected in the diurnal period. The bactericidal activity of PMN phagocytes against EPEC was higher when bacteria were opsonized and in samples collected in the diurnal period. For opsonized S. pneumoniae, phagocytes had similar bactericidal activity, irrespective of colostrum collection period. These data support the hypothesis that there is a fluctuation in the functional activity of colostral phagocytes, which is dependent on synchronization among feeding time, pathogen features and infection area.

Differentiation between Viral and Bacterial Acute Infections Using Chemiluminescent Signatures of Circulating Phagocytes

Oftentimes the etiological diagnostic differentiation between viral and bacterial infections is problematic, while clinical management decisions need to be made promptly upon admission. Thus, alternative rapid and sensitive diagnostic approaches need to be developed. Polymorphonuclear leukocytes (PMNs) or phagocytes act as major players in the defense response of the host during an episode of infection, and thereby undergo functional changes that differ according to the infections. PMNs functional activity can be characterized by quantification and localization of respiratory burst production and assessed by chemiluminescent (CL) byproduct reaction. We have assessed the functional states of PMNs of patients with acute infections in a luminol-amplified whole blood system using the component CL approach. In this study, blood was drawn from 69 patients with fever (>38 °C), and diagnosed as mainly viral or bacterial infections in origin. Data mining algorithms (C4.5, Support Vector Machines (SVM) and Naïve Bayes) were used to induce classification models to distinguish between clinical groups. The model with the best predictive accuracy was induced using C4.5 algorithm, resulting in 94.7% accuracy on the training set and 88.9% accuracy on the testing set. The method demonstrated a high predictive diagnostic value and may assist the clinician one day in the distinction between viral and bacterial infections and the choice of proper medication.

Human colostral phagocytes eliminate enterotoxigenic Escherichia coli opsonized by colostrum supernatant

Several elements in colostrum and human milk, including antibodies and nonspecific factors with bactericidal and antiviral activity, may play an important anti-infectious and protective role. In developing countries, enterotoxigenic Escherichia coli (ETEC) is the main etiological agent of diarrhea in low-socioeconomic level children. In the present work, we studied the functional activity of mononuclear (MN) and polymorphonuclear (PMN) phagocytes of human colostrum against ETEC, as well as the interactions between these cells and colostral or serum opsonins. Colostrum samples were collected from 33 clinically healthy women between 48 and 72 hours postpartum. We verified superoxide release in colostral MN and PMN using cytochrome C reduction methods, phagocytosis, and bactericidal activity using acridine orange methods and superoxide dismutase (SOD) in the colostrum supernatants. Colostral MN and PMN phagocytes exposed to ETEC opsonized with colostrum supernatants caused a significant increase (p<0.05) in superoxide release. Phagocytosis by colostral PMN cells increased significantly (p<0.5) when the phagocytes were incubated with both sources of opsonins (sera and colostrum). Increases in superoxide release in the presence of opsonized bacteria triggered the bactericidal activity of the phagocytes. Phagocyte treatment with SOD decreased their ability to eliminate ETEC. Colostrum supernatant had higher SOD concentrations (p<0.05) compared with normal human sera. These results suggest that the ability of phagocytes to eliminate ETEC depends on the activation of cellular oxidative metabolism; moreover, activation of colostral phagocytes is likely an additional breast-feeding protection mechanism against intestinal infections in infants.

Time-dependent alterations of soluble and cellular components in human milk

This study sought to determine the chronobiological variations in soluble and cellular components of human breast milk. The material was collected from 36 mothers at three stages of maturity – 3 days (colostrum), 10 days (transitional milk) and 30 days (mature milk) postpartum – and at two times of day – diurnal (12:00 h) and nocturnal (24:00 h) – making a total of 216 samples. Fat and calorie content, antibody concentration, C3 and C4 proteins of the complement system, superoxide anion release by milk mononuclear (MN) and polymorphonuclear (PMN) phagocytes, and concentration of the superoxide dismutase enzyme (CuZn-SOD) were determined. No difference in fat concentration was found between milk collected at the different times or between milk maturation stages but in the transitional milk the calorie concentration was higher in the nocturnal period. IgA was higher in milk collected in the diurnal period regardless of milk maturation. IgG and IgM were at higher concentrations in the diurnal period for both transitional and mature milk. The C3 protein increased significantly in the diurnal period regardless of milk maturation, and the C4 protein increased significantly during the diurnal period in the colostrum and transitional milk stages. Mature milk MN phagocytes had the highest superoxide during the diurnal period. Superoxide release by PMN phagocytes was higher in colostrum and mature milk collected in the diurnal period. CuZn-SOD increased significantly in diurnal and nocturnal colostrum. This chronobiological variation during the first month postpartum may represent an additional breastfeeding mechanism to improve adaptation to environmental changes and establish biological rhythms in the temporal synchronization process.

Roles of inflammatory cells in the pathogenesis of acute lung injury in guinea pigs exposed to heat-killed bacteria

To study the contribution of polymorphonuclear (PMN) and mononuclear (MN) phagocytes to the development of acute lung injury, we studied lung injury after intratracheal instillation of lipopolysaccharide (0.02 mg/kg) in guinea pigs previously exposed to heat-killed Corynebacterium parvum. In on group, cyclophosphamide was given to deplete peripheral PMNs. In another group, gadolinium chloride (GdCl3) was injected to suppress the function of MNs. Four hours after instillation of lippoly soccharide, the animals were killed, bronchoalveolar lavage was done, and the lungs were examined histopathologically. 125I-labeled albumin was injected to estimate the endothelial damage, and 131I-labeled albumin was injected to correct for blood contamination in the samples. In the group given cyclophosphamide, lung injury was no less than in the control group. In contrast, lung injury was less sever in the group given GdCl3 than in the control group. These findings suggest that MN are important in the pathogenesis of lung injury, especially in individuals who are immunologically primed by infection.