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PubMed1977

Determination of the bacteriostatic capacity of neutrophils and monocytes in mixed cell populations.

Cline [1, 2] described a method of determining the phagocytic and bacteriostatic activity of individual types of leukocytes within mixed cell populations. We tried to improve the applicability of this method for the investigation of clinical problems.--Bacteria in the log-phase of growth were incubated in test tubes with leukocytes separated from venous blood. After a short period of phagocytosis 3H-thymidine was added to label DNA-synthesizing organisms. Smears were prepared and processed by autoradiography. The labeling indices of extracellular bacteria and of those phagocytized by neutrophils and monocytes were determined microscopically. The intracellular inhibition of DNA-synthesis was taken as indicative of the bacteriostatic activity of the leukocytes. The proposed modification of Cline's assay is suited to investigate clinical problems of phagocyte dysfunction.

Autoradiography↗
PubMed1986

Neutrophil subpopulations change after thermal injury.

Just as there are subpopulations of mononuclear leukocytes which are functionally distinct, so there appear to be different subpopulations of neutrophils, with different functional abilities. Neutrophils which display the Fc receptor (Fc+) for immunoglobulin have increased chemotactic phagocytic and bactericidal activity compared with neutrophils which are Fc receptor negative (Fc-). To determine if the acquired neutrophil dysfunction which occurs after thermal injury could be due to a change in the percentage of Fc+ neutrophils, serial studies of neutrophil function, including random migration, chemotaxis, phagocytosis, and killing of Staphylococcus aureus, were performed in 12 patients and related to the percentage of neutrophils which possessed the Fc receptor. After thermal injury the percentage of Fc+ cells decreased significantly (p less than 0.01). However, no correlation between the number of rosette-forming cells and random migration (p = 0.48), chemotaxis (p = 0.45), or bactericidal activity (p = 0.50) was found in this patient population. Thus, although thermal injury was associated with a significant decrease in the number of Fc+ neutrophils, this change in neutrophil subpopulation levels did not explain the acquired defect in neutrophil function which occurred after thermal injury.

Adult↗
PubMed1977

Postsurgical granulocyte dysfunction: studies in healthy kidney donors.

In order to determine whether surgical trauma affects granulocyte function, we performed sequential studies of granulocyte phagocytic and bactericidal function, chemotaxis, and adherence on 25 otherwise healthy subjects undergoing donor nephrectomy for kidney transplantation. All values were normal prior to surgery, and bacterial killing and phagocytosis were unaffected by surgery. Granulocyte chemotaxis and adherence were significantly impaired immediately following surgery, returning to normal in 24 hr. Anesthesia alone did not affect chemotaxis. Generation of chemoattractants from postoperative plasma was normal, and inhibitors of chemotaxis could not be demonstrated, suggesting an intrinsic cellular defect. We suggest that these postoperative abnormalities of granulocyte chemotaxis and adherence may contribute to the high incidence of infectious complications following surgery.

Cell Adhesion↗
PubMed1988

[Ultrastructural manifestations of the membrane activity of neutrophilic leukocytes].

Phagocytic function of neutrophils is associated with activation of cell membranes. Neutrophil membranous activity is considered for patients with inflammatory and purulent diseases. It appeared not uniform and served the basis for division the neutrophils into three groups. Group I neutrophils are inactive, being not involved in phagocytosis, but bearing bactericidal potential; their membranes are stable. Group II neutrophils show moderate activity, phagocytizing and inactivating bacteria; phagocytosis proceeds without cell destruction. Group III neutrophils cause membranes hyperactivation with resultant dysfunction of phagocytes, phagocytosis involves both bacteria and surrounding protein substrates, immature phagosomes and vacuoles are produced, membranes are unstable. With aggravation of the inflammation and suppuration, the number of blood hyperactivated neutrophils increases.

Blood Bactericidal Activity↗
PubMedDate not supplied

Depression of neutrophil function induced by viruses and its role in secondary microbial infections.

A large body of evidence has accumulated indicating that viruses can predispose animal and human hosts to secondary local and systemic bacterial and fungal disease. The mechanism by which viruses cause these superinfections involves both a direct effect of viruses on the tissues at the site of infection and alterations in cells involved in immune surveillance. The effect of viruses on lymphocytes, monocytes, and macrophages has recently been reviewed. A number of viruses have been shown to depress various functions of polymorphonuclear leukocytes, which are critical for controlling bacterial and fungal infections. The alterations in functions of polymorphonuclear leukocytes induced by different viruses include abnormalities of adherence, chemotaxis, phagocytic, oxidative, secretory, and bactericidal activities. The effect of various viruses on neutrophils and the role that virus-induced neutrophil dysfunction has in predisposing the host to secondary infections are reviewed.

Animals↗
PubMedDate not supplied

Functional evaluation of human neutrophils. Is the bactericidal activity correlated with nitroblue tetrazolium reduction?

The cytochemical nitroblue tetrazolium (NBT) reduction test continues to be used in clinical laboratories to detect defects in the oxidative metabolism of phagocytes. However, the specificity of the test is controversial, and it is not clear whether NBT reduction really reflects the microbicidal activity of these cells. In the present study, we evaluated the killing of Staphylococcus aureus by neutrophils from healthy adult individuals and from patients with phagocyte dysfunctions using a fluorochrome phagocytic assay, and compared the results with those obtained with a cytochemical NBT test performed simultaneously. The ability of neutrophils to reduce NBT (expressed as percent reducing neutrophils) with or without a lipopolysaccharide stimulus was not correlated with the bactericidal activity of these cells (expressed as percent killed bacteria per 100 neutrophils). The age and sex of the healthy adults did not influence the results of either assay. It seems that the superoxide anion played a small role in NBT reduction by normal neutrophils, since superoxide dismutase did not significantly inhibit this reaction. Only the absolute absence of NBT reduction reflected the low bactericidal activity of neutrophils, as seen in patients with chronic granulomatous disease (CGD). We conclude that the only clinical usefulness of the NBT test is for the screening of CGD, and that bacterial phagocytic assays are more appropriate for assessing the microbicidal function of neutrophils.

Adolescent↗
PubMed1983

Lung macrophage defense responses during suramin-induced lysosomal dysfunction.

Lysosomes form an integral part of the degradative mechanisms of the phagocytic cells. Mice were injected with suramin, a lysosomotrophic drug, to investigate the effects of lysosomal pathology on the cell biology and in situ bactericidal activity of the pulmonary macrophage. Treatment with suramin resulted in marked alterations in the cell biology of the macrophage: (i) increased vacuolization and protein content, (ii) suppressed intracellular phagosome-lysosome fusion, (iii) decreased activity of the lysosomal enzymes beta-glucuronidase and N-acetyl-glucosaminidase, and (iv) enhanced exocytosis of acid phosphatase during phagocytosis. Addition of suramin, in vitro, to cell lysates resulted in a reduction in the catalytic activities of acid phosphatase, beta-glucuronidase, and N-acetyl-glucosaminidase; thereby suggesting that selective interaction, in vivo, between suramin and lysosomes containing beta-glucuronidase and N-acetyl-glucosaminidase may have occurred. Plasma membrane 5'-nucleotide phosphodiesterase activity was increased in macrophages recovered from suramin-treated animals. Although the "resting-state" reduction of nitroblue tetrazolium (NBT) was lower in these macrophages, cells stimulated by a phagocytic challenge demonstrated normal increases in NBT reduction. Phagocytosis, in vitro, and pulmonary bactericidal activity were not altered. These data demonstrate that suramin altered numerous aspects of the phagocyte's lysosomal system. Despite these changes in the cell biology of the pulmonary macrophage, the cell's defense functions were not reduced.

Acetylglucosaminidase↗
PubMed1993

Effect of the HELLP syndrome on maternal immune function.

The HELLP syndrome occurs in less than 1% of gravidas and is characterized by hemolysis, elevated liver enzymes and low platelet count. The status of immune function in these high-risk patients is not known but may be of great importance in better understanding the basis, if any, of immune dysfunction in pregnancy-associated hypertensive disorders and from the potential compounding effect of infection upon an already debilitated patient. We assessed maternal immune status in patients with the HELLP syndrome using conventional in vitro techniques. The results of these studies clearly show a depression of both T and B cell potential and impaired monocyte handling of intracellular pathogens (up to 33%, 11% and 17% of control values, respectively). The onset of this immunosuppression occurred before the clinical diagnosis of HELLP syndrome was made and persisted for at least 14 days after clinical resolution. Results of cell admixture studies suggest that these effects are mediated by accessory cells or their products and do not represent true lymphocyte dysfunction. The risk of opportunistic infections may therefore be increased in the patient with the HELLP syndrome because of this generalized immunosuppression and profound decrease in monocyte phagocytic and bactericidal activity.

Adult↗
PubMed1979

Alveolar macrophage dysfunction associated with viral pneumonitis.

Viral infections are known to predispose to bacterial infections of the lung. Studies on the virus-induced suppression of pulmonary bactericidal mechanisms have identified the defect with abnormalities in the alveolar macrophage phagocytic system. In the investigation presented herein, we have dissected some of the subcomponents of the phagocytic process and found virus-induced defects in phagocytic ingestion, phagosome-lysosome fusion, and intracellular killing.

Acid Phosphatase↗
PubMed2003

Oxidative killing of microbes by neutrophils.

Neutrophils and other phagocytic leukocytes contain a phagocyte NADPH oxidase enzyme that generates superoxide after cell activation. Reactive oxygen species derived from superoxide, together with proteases liberated from the granules, are used to kill ingested microbes. Dysfunction of the phagocyte NADPH oxidase results in chronic granulomatous disease, with life-threatening infections.

Blood Bactericidal Activity↗
PubMed1991

Liver bacterial clearance following hepatic artery ligation and portacaval shunt.

The reticuloendothelial system (RES) plays an important role in removing bacteria, endotoxins, and immune complexes from the circulation. Hepatic phagocytosis accounts for more than 80% of RES function. The dual hepatic blood supply (hepatic artery/portal vein) may be altered by pathologic states and surgical procedures. This study evaluates and compares the effect of hepatic artery ligation and portacaval shunt on hepatic trapping of viable Escherichia coli. Thirty rats were placed in three groups: Group I was composed of sham operated controls; Group II underwent end-to-side portacaval shunt (PCS); and in Group III, hepatic artery ligation (HAL) was performed. At 2 weeks following the operation 10(9) 35S-radiolabeled viable E. coli were injected via the tail vein. At 10 min, bacterial distribution in the different organs was determined. Tissue samples were processed for liquid scintillation counting. The final distribution of bacteria was calculated from the input specific activity (dpm/bacteria) and expressed as the mean percentage of injected viable E. coli per gram of tissue and per organ weight. There was a significant decrease of bacterial trapping by the liver in rats following PCS (Group II), 45.0 +/- 10.4% vs controls 77.1 +/- 3.73% (P less than 0.005). This was partially compensated for by a significant increase of bacterial trapping by the lung. The decreased clearance in PCS rats is due to a reduction in liver mass compared to that in controls. Bacterial localization in HAL (Group III) rats was similar to that in controls. These data show that PCS decreases hepatic clearance and increases pulmonary localization of viable E. coli. This phagocytic dysfunction may contribute to increased susceptibility to infection following portacaval shunt.

Animals↗
PubMed1975

Neutrophil granulocyte function in the early diagnosis of acute myelomonocytic and myeloblastic leukaemia.

The phagocytic and bactericidal activities of neutrophil granulocytes from 5 patients with early acute myelomonocytic or myeloblastic leukaemia and 5 controls have been examined. In each patient the bactericidal activity was lower than in any control and the neutrophil dysfunction was demonstrated before leukaemia could be diagnosed from clinical and haematological findings. During periods of remission, the bactericidal activity was normal. Results of neutrophil granulocyte function studies may be a significant aid in the early diagnosis of acute myelomonocytic and myeloblastic leukaemia.

Adult↗
PubMed2001

Clinical features of a human Rac2 mutation: a complex neutrophil dysfunction disease.

The case of an infant with multiple, rapidly progressive, soft-tissue infections is presented. Despite features suggesting a neutrophil disorder, results of screening tests of phagocyte function were normal. A novel, multifaceted leukocyte disorder-distinguished by defects in shape change, chemotaxis, ingestion, degranulation, superoxide anion production, and bactericidal activity-was established secondary to a defect in Rac2.

Blood Bactericidal Activity↗
PubMed1990

Pulmonary antibacterial defenses during mild and severe influenza virus infection.

Severe influenza virus infections with pneumonic involvement are known to predispose the lungs to bacterial superinfections due to dysfunctions in the alveolar macrophage (AM) phagocytic system. To determine whether milder forms of influenza without pneumonic involvement have a similar outcome, pulmonary antibacterial defenses and AM phagocytosis were compared in murine models of mild and severe influenza virus A/HK/68 infections. Bactericidal activity was quantitated by the intrapulmonary killing of Staphylococcus aureus following aerosol challenge, whereas the functional capacity of the AMs was determined by Fc-receptor-mediated phagocytosis. With the severe virus infection, maximal suppression of bactericidal activity occurred on day 8 of infection and correlated with impairment of AM phagocytosis. A lesser but significant degree of suppression of pulmonary antibacterial defenses and AM phagocytosis was observed on the third day of the mild virus infection. The data demonstrate that mild influenza virus infections that are limited to the upper respiratory tract also impair pulmonary antibacterial defenses and may predispose the lungs to bacterial superinfections.

Animals↗
PubMed1986

Altered functions of peripheral blood monocytes in homosexual males and intravenous drug users with persistent generalized lymphadenopathy.

Persistent generalized lymphadenopathy (PGL) is observed predominantly in subjects at risk of developing AIDS. Twenty-seven individuals belonging to such groups: twelve homosexual males and fifteen intravenous drug users, were investigated for immunological abnormalities with particular attention to monocyte functions. They were compared with five AIDS patients. Twenty out of twenty-two individuals had anti-LAV/HTLV-III antibodies and most had abnormalities characteristic of AIDS: polyclonal hypergammaglobulinemia, decreased cell-mediated immunity, inverted T-cell helper/suppressor ratio and histological alterations of lymph nodes. As for peripheral blood monocyte functions, phagocytic capacity and production of O2- were normal and bactericidal capacity was decreased. Monocytes cultured in the presence of concanavalin A produced less PGE2 and more IL-1/MCF than normal monocytes. Similar abnormalities were found using monocytes from AIDS patients. These data suggest that monocytes from patients with PGL have functional alterations that may be either intrinsic or secondary to lymphocyte dysfunction(s); these alterations do not account for the decreased capacity of lymphocytes to respond to mitogens but may explain the uncontrolled activation of B cells.

Acquired Immunodeficiency Syndrome↗
PubMed1973

Role of immunity in viral-induced bacterial superinfections of the lung.

Although viral illnesses are predisposing causes for pulmonary bacterial infections, the interrelationships of viral virulence and host immunity to alterations in susceptibility to bacterial infection are incompletely understood. We used two mutant strains of encephalomyocarditis virus (minimally virulent Mengo-37A and a highly virulent Columbia SK [Col-SK]) to investigate these interrelationships. Mice that had been immunized to Mengo-37A, and nonimmunized controls, were challenged with aerosols containing 10(4) plaque-forming units of Mengo-37A or Col-SK per liter. The effect of each viral infection on pulmonary antibacterial activity was assessed 3 days later by measuring the capacity of the lungs to kill inhaled radiophosphorus ((32)P)-labeled Staphylococcus aureus. The degree of antibacterial dysfunction found was proportional to the virulence of the infecting virus. If the host was immune to the infecting virus, bactericidal function was not impaired by viral challenge. Neither mutant caused significant pulmonary damage; therefore: (i) viral-induced impairment in bactericidal activity reflects, quantitatively, the virulence of the virus and (ii) viral immunity protects pulmonary bacterial defenses by preventing damage to the phagocyte from the virus or its attendant metabolic abnormalities.

Aerosols↗
PubMed1991

Impaired phagocytosis in dialysis patients: studies on mechanisms.

Dialysis patients have increased susceptibility to infection and this is, in part, due to impaired phagocytic and bactericidal activities of polymorphonuclear leukocytes (PMNL). The mechanisms responsible for the reduced phagocytosis are not known. Dialysis patients have elevated blood levels of parathyroid hormone (PTH), and available data indicate that PMNL is a target cell for PTH. Chronic exposure to excess PTH may cause accumulation of calcium in PMNL which in turn could adversely affect cellular events leading to their dysfunction. We studied phagocytosis, resting levels of cytosolic calcium [( Ca2+]i), ATP content and the rise in [Ca2+]i in response to ligation of Fc gamma RIII receptors with 3G8 monoclonal antibody in PMNL from 37 dialysis patients and 48 normal subjects. The PMNL from the dialysis patients displayed impaired phagocytosis, elevated resting levels of [Ca2+]i, decreased ATP content and a smaller rise in [Ca2+]i in response to various doses of 3G8 monoclonal antibody as compared to values obtained in PMNL of normal subjects. Our results suggest that derangements in cellular metabolism and possibly an abnormality in Fc gamma RIII interaction with antibody and/or the consequences of such interaction are responsible, at least in part, for the impaired phagocytosis of PMNL of dialysis patients. Our data are consistent with the notion that excess PTH may play an important role in the processes leading to impaired phagocytosis.

Adenosine Triphosphate↗
PubMed2005

Is immunity in diabetic patients influencing the susceptibility to infections? Immunoglobulins, complement and phagocytic function in children and adolescents with type 1 diabetes mellitus.

OBJECTIVE: Previous reports suggest an increased susceptibility of diabetes patients to infections, but little information is available on possible underlying immunologic dysfunctions. The aim of this study was to evaluate humoral factors in pediatric patients with type 1 diabetes mellitus. METHODS: There were 66 diabetic patients (39 males:27 females; 5-17 yr) classified into two groups according to levels of glycohemoglobin (limit 9%): Group C - controlled (n = 33) and Group UC - uncontrolled (n = 33). We evaluated five patients in C and six in UC who reported previous infections. Immunologic analysis included measurement of plasma concentrations of immunoglobulins (Ig), C3, and C4 levels (turbidimetry); functional hemolytic assays for complement evaluation (CPH for classical and APH for alternative pathways), quantification of C4 isotypes C4A and C4B (ELISA), phagocytosis assays, measurement of bactericidal activity against Staphylococcus aureus, as well as tests of fungicidal capacity for Candida albicans. RESULTS: The UC Group had higher mean age, received higher insulin doses, and had higher concentrations of glycohemoglobin than the C Group. No significant differences in duration of the disease or nutritional conditions were detected between the groups. Lower IgA values in C (10/33) and lower IgG levels in UC (23/33) were detected, and there were inverse relationship with HbA1c values. Analysis of CPH, APH, C3, and C4 showed normal levels in both groups and no statistical correlation with the HbA1c. However, 9/33 children of the UC Group had decreased C3 values. C4B levels were below the normal range in 8/20 and correlated with higher HbA1c. Both phagocytic assays for S. aureus and Candida albicans were within normal limits. CONCLUSIONS: Low IgG concentrations and to some degree reduction in C4B levels were related to impaired metabolic control. No strong link between the immunological alterations was found in diabetic patients and the occurrence of infections.

Adolescent↗