Cleavage of complement C3b to iC3b on the surface of Staphylococcus aureus is mediated by serum complement factor I.

Complement-mediated opsonization of Staphylococcus aureus bearing the dominant capsule serotypes, serotypes 5 and 8, remains incompletely understood. We have previously shown that complement plays a vital role in the efficient phagocytosis of a serotype 5 S. aureus strain and that the opsonic fragments of the central complement protein C3, C3b and iC3b, were present on the bacterial surface after incubation in human serum. In the present studies, C3b and iC3b were found on several serotype 5 and 8 S. aureus strains after incubation in human serum. Using purified classical activation pathway complement proteins and the Western blot assay, we showed that when C3b was generated on the S. aureus surface no iC3b fragments were found, suggesting that other serum proteins may be required for cleaving C3b to iC3b. When C3b-coated S. aureus was incubated with serum factor I, a complement regulatory protein, iC3b was generated. Purified factor H, a serum protein cofactor for factor I, did not enhance factor I-mediated cleavage of C3b. These findings suggest that C3b cleavage to iC3b on S. aureus is mediated by serum factor I and does not require factor H.

Intracellular effect of ultrashort electrical pulses.

A simple electrical model for biological cells predicts an increasing probability for electric field interactions with cell substructures of prokaryotic and eukaryotic cells when the electric pulse duration is reduced into the sub-microsecond range. The validity of this hypothesis was verified experimentally by applying electrical pulses with electric field intensities of up to 5.3 MV/m to human eosinophils in vitro. When 3-5 pulses of 60 ns duration were applied to human eosinophils, intracellular granules were modified without permanent disruption of the plasma membrane. In spite of the extreme electrical power levels applied to the cells thermal effects could be neglected because of the ultrashort pulse duration. The intracellular effect extends conventional electroporation to cellular substructures and opens the potential for new applications in apoptosis induction, gene delivery to the nucleus, or altered cell functions, depending on the electrical pulse conditions.

Human milk anti-inflammatory component contents during acute mastitis.

Mastitis is a common complication of human lactation. We examined milk specimens from eight women with clinical mastitis to determine their content of anti-inflammatory components. Antioxidant activity (spontaneous cytochrome c reducing activity), selected pro-inflammatory cytokines (IL-6, IL-1beta), selected endogenous cytokine control molecules (sIL-6R, sIL-1RII, and sTNFRI), lactoferrin, Na(+):K(+) ratios, and milk bioactivities that cause shedding of sIL-1RII from human polymorphonuclear leukocytes (PMN), suppress PMN aggregation, and suppress PMN adherence responses were not increased compared to normal milks. Neither the bioactivities that deplete PMN intracellular Ca(2+) stores nor those that block Ca(2+) influx into fMLP-stimulated PMN were significantly increased in mastitis milks. In contrast, levels of TNFalpha, sTNFRII, and IL-1RA and bioactivities that cause shedding of sTNFRI from human PMN were significantly increased compared to normal milks. Mastitis milk has the same anti-inflammatory components and characteristics of normal milk, with elevations in selected components/activities that may help protect the nursing infant from developing clinical illness due to feeding on mastitis milk.

Anti-inflammatory characteristics of human milk: how, where, why.

When first proposed, the hypothesis that human milk was anti-inflammatory was supported by 2 observations: poor function of milk leukocytes and the presence in milk of components that could modify inflammatory processes. This hypothesis is now supported by studies documenting anti-inflammatory effects in animal models and suppression of humoral and cellular components of inflammation in vitro. To date, two mechanisms have been demonstrated: alteration of leukocyte function and modification of cytokine biology. It is not clear whether these mechanisms are only topical effects in the digestive tract, or whether absorption of milk components results in systemic effects. While inflammation benefits the host as a defense mechanism and precursor to immune responses, it also contributes to the clinical manifestations of illness and is an important early component of wound-healing responses that result in scar. The biological effects of milk's anti-inflammatory character may be to minimize clinical symptomatology without losing immunoresponsiveness for the breast-fed infant, and to minimize scar formation during healing responses.

Release of cytokines and soluble cytokine receptors after intravenous anti-D treatment in children with chronic thrombocytopenic purpura.

INTRODUCTION: Immunoglobulin anti-D administration is one of several methods used in treating children with chronic immune thrombocytopenic purpura. Fc receptor blockade of the reticuloendothelial cell system and of mononuclear phagocytes is an important mechanism of the action of anti-D in ITP. Recently other possible mechanisms by which anti-D works in ITP have been considered. METHODS: The aim of this study was to obtain a better understanding of the effect of anti-D administration on cytokine, soluble cytokine receptors and platelet count in children with chronic ITP and to determine the pre-treatment plasma cytokine profile in this group of patients. Eighteen children with chronic ITP were examined. In our study the impact of anti-D on the cytokine network was evaluated by analysing serum levels of IL-6, IL-8, tumor necrosis alpha and soluble TNF receptors I and II by the EASIA method before and 1, 3, 20 and 40 h then seven days and one month after anti-D infusion. RESULTS: Anti-D caused a significant increase in platelet count 20 h postinfusion in 10 out of 18 children, 96 h postinfusion in three children and 168 h postinfusion in one child. The mean duration of the response was four weeks. A significant and rapid increase in plasma levels of IL-6, IL-8 and TNF-alpha was seen within 1 to 20 h after anti-D infusion. This increase was accompanied by a prolonged elevation of soluble TNF receptors. There was a significant correlation between TNF-alpha and IL-8, IL-8 and IL-6, TNF-alpha and sTNFRI, and sTNF receptors I and II. CONCLUSION: These data demonstrate that anti-D infusion caused changes in the cytokine network and raises the question of whether the therapeutic effectiveness of anti-D is related to its immunomodulating properties.

Should central venous catheters be removed as soon as candidemia is detected in neonates?

BACKGROUND: Controversy exists regarding the most appropriate acute management of central venous catheters (CVCs) in neonates with candidemia, with up to two thirds of neonatologists preferring to attempt antifungal therapy without removing CVCs. OBJECTIVE: To determine whether CVCs should be removed as soon as candidemia is detected in neonates. Methods. A cohort study of candidemia and CVC was conducted in infants in a neonatal intensive care unit (NICU) over a 5-year period (1994-1998). RESULTS: Fifty infants had early-removal CVC (ER-CVC) within 3 days and 54 infants had late-removal CVC (LR-CVC) >3 days after the first positive blood culture for Candida species. All infants were treated with amphotericin B. There was no significant difference between infants in the ER-CVC and LR-CVC groups in terms of gender, ethnicity, birth weight, gestational age, age at candidemia, severity-of-illness scores, distribution of types of CVC, or in the distribution of Candida species causing candidemia. The ER-CVC group had significantly shorter duration of candidemia (median: 3 days; range: 1-14 days), compared with the LR-CVC group (median: 6 days; range: 1-24 days). The case fatality rate of Candida albicans candidemia was significantly affected by the timing of CVC removal: 0 of 21 (95% confidence interval [CI]: 0-14) infants died in the ER-CVC group in contrast to 9 of 23 (39%; 95% CI: 19-59) in the LR-CVC group. CONCLUSION: Failure to remove CVC as soon as candidemia was detected in neonates was associated with significantly increased mortality in C albicans candidemia and prolonged duration of candidemia regardless of Candida species.

Surfactant modulates calcium response of neutrophils to physiologic stimulation via cell membrane depolarization.

Pulmonary surfactant (PS) reduces inflammation in the lung by poorly understood mechanisms. We have observed that surfactant-associated proteins (SAP) insert monovalent cation channels in artificial membranes. Neutrophils are primary mediators of acute pulmonary inflammation, and their functions are activated by increases in cytosolic ionized calcium concentration ([Ca2+]) and by changes in membrane potential. We hypothesize that PS inserts SAP-dependent cation channels in neutrophils, causing membrane depolarization, altered [Ca2+] response, and depressed activation. Human neutrophils were isolated, exposed to PS+SAP (1% Survanta), PS-SAP (1% Exosurf), or buffer, and washed before activating with selected stimulants. PS+SAP reduced phorbol ester- and formyl peptide-stimulated adherence and aggregation by 38% (p < 0.05) and 54% (p < 0.02), respectively. PS+SAP also inhibited the formyl peptide-induced [Ca2+] response of neutrophils (p < 0.01), but only in the presence of external Ca2+. Further characterization of this inhibition demonstrated that PS+SAP blocked formyl peptide-induced influx of both Ca2+ and Mn2+, and that this inhibition was present during activation by other neutrophil stimulants (IL-8, immune complexes). Prior depolarization of neutrophils with gramicidin-D similarly inhibited the [Ca2+] response of neutrophils to formyl peptide, and analysis of neutrophil membrane potential by 3,3'-dipentyloxaearbocyanine iodide (diOC5(3)) fluorescence revealed that PS+SAP induced rapid neutrophil depolarization. In contrast, PS-SAP exhibited little effect on neutrophil function, [Ca2+], or membrane potential. We conclude that PS+SAP decreases neutrophil adherence and aggregation responses, blocks Ca2+ influx after physiologic stimulation, and decreases membrane potential. We speculate that these effects are caused by membrane depolarization via SAP-dependent cation channel insertion, and that all of these effects contribute to the antiinflammatory properties of PS+SAP.

Fulminant late-onset sepsis in a neonatal intensive care unit, 1988-1997, and the impact of avoiding empiric vancomycin therapy.

OBJECTIVE: To determine the pathogens associated with fulminant (lethal within 48 hours) late-onset sepsis (occurring after 3 days of age) in a neonatal intensive care unit (NICU) and the frequency of fulminant late-onset sepsis for the most common pathogens. METHODS: A retrospective study was conducted of sepsis in infants in a NICU over a 10-year period (1988-1997). RESULTS: There were 825 episodes of late-onset sepsis occurring in 536 infants. Thirty-four of 49 (69%; 95% confidence interval [CI]: 55%-82%) cases of fulminant late-onset sepsis were caused by Gram-negative organisms, including Pseudomonas sp., 20 (42%); Escherichia coli, 5 (10%); Enterobacter sp., 4 (8%); and Klebsiella sp., 4 (8%). The frequency of fulminant sepsis was highest for Pseudomonas sp., 20 of 36 (56%; 95% CI: 38%-72%) and lowest for coagulase-negative staphylococci, 4 of 277 (1%; 95%CI: 0%-4%). The very low frequency of fulminant sepsis caused by coagulase-negative staphylococci did not increase during the period when oxacillin was used instead of vancomycin as the empiric antibiotic for Gram-positive organisms. CONCLUSIONS: These data suggest that empiric antibiotics selected for treatment of suspected sepsis in infants >3 days old need to effectively treat Gram-negative pathogens, particularly Pseudomonas sp., because these organisms, although less frequent, are strongly associated with fulminant late-onset sepsis in the NICU. Avoiding empiric vancomycin therapy seemed to be a reasonable approach to late-onset sepsis, because of the very low frequency of fulminant sepsis caused by coagulase-negative staphylococci.

Human milk effects on neutrophil calcium metabolism: blockade of calcium influx after agonist stimulation.

Neutrophils are the predominant cellular mediators of acute inflammation, and human milk suppresses multiple neutrophil functions. We sought to determine whether these effects were mediated through disruption of normal intracellular Ca2+ homeostasis. Exposure of human neutrophils to human milk, followed by washing, resulted in altered Ca2+ transient responses to formyl-peptide stimulation in which the peak cytosolic free Ca2+ concentration ([free Ca]) was the same as in unexposed cells, but the postpeak decline in [free Ca] was more rapid. This effect was observed after human milk exposures as brief as 10 s, persisted for up to 4 h after human milk removal, and was concentration dependent. On the basis of experiments examining Ca2+-free conditions followed by Ca2+ supplementation, and experiments examining spontaneous and stimulated manganese and barium influx into neutrophils, the human milk effect was due to blockade of Ca2+ influx. Decreased Ca2+ transient responses to other physiologic stimuli (IL-8, opsonized Staphylococcus aureus, and immune complexes) were observed after human milk exposures. Rat intestinal epithelial cells and HL-60 cells failed to show these effects, suggesting a selective effect on mature inflammatory cells. Characterization of the Ca2+-blocking activity showed it was heat and acid stable in human milk with a molecular mass between 30-100 kD. Commercial human milk lactoferrin exhibited Ca2+ influx blockade activity, but recombinant human lactoferrin showed none. Separation of the activity by heparin affinity chromatography showed that it was distinct from lactoferrin. Human milk-induced blockade of Ca2+ influx provides a potential mechanism for broad suppression of neutrophil functions that may contribute to the antiinflammatory properties of human milk.

Membrane depolarization and depletion of intracellular calcium stores are associated with delay of apoptosis in human neutrophils.

Apoptosis occurs rapidly in human polymorphonuclear leukocytes (PMN) after exposure to 1 mM cycloheximide (CHX). We examined whether this form of stimulated apoptosis altered either resting cytosolic free Ca2+ concentrations ([free Ca]) or membrane potential (psi) in PMN and found no significant effects. However, manipulation of either PMN intracellular Ca2+ stores or psi was found to delay CHX-induced apoptosis. Depletion of PMN intracellular Ca2+ stores with thapsigargin caused membrane depolarization and significantly delayed CHX-induced apoptosis based on both morphological and annexin-V-fluorescein isothiocyanate binding criteria. Short-term suspension (4 h) of PMN in Ca2+-free buffer depleted internal Ca2+ stores, induced membrane depolarization at 2.5 h, and delayed spontaneous (24 h) apoptosis but had no effect on CHX-induced apoptosis. Rapid membrane depolarization with 150 mM KCl buffer significantly delayed CHX-induced apoptosis, suggesting that depolarization rather than Ca2+ stores depletion was the crucial event. Timing experiments revealed that depolarization within 12 min of CHX exposure significantly delayed apoptosis. Collectively, these observations suggest an early psi-sensitive step in the apoptosis pathway initiated by CHX. CHX exposure alone does not alter either resting PMN [free Ca] or psi; accompanying depolarization of plasma membrane (either electrochemically or via depletion of internal Ca2+ stores) delays CHX-induced apoptosis in a time-dependent manner.

Candidemia in a neonatal intensive care unit: trends during fifteen years and clinical features of 111 cases.

OBJECTIVE: To determine changes in the incidence of candidemia in a neonatal intensive care unit (NICU) during a 15-year period (1981 to 1995) and to compare the prevalence and case fatality rates of Candida albicans and Candida parapsilosis infections. METHODS: A retrospective study was conducted of candidemia occurring in infants in a NICU between January 1, 1981, and December 31, 1995. Cases were identified through computerized searching of a microbiology blood culture database. Candidemia was considered contributory to mortality if death occurred within 3 days of positive blood cultures or if there was autopsy evidence of disseminated candidiasis. RESULTS: One hundred eleven cases of candidemia occurred in 107 infants, representing 1% of all NICU patients during the study period. The rate of candidemia in the NICU increased from 2.5 cases per 1000 admissions in 1981 to 1985, to 4.6 per 1000 admissions in 1986 to 1990 and to 28.5 per 1000 in 1991 to 1995 (P = 0.001). C. albicans was the predominant cause of candidemia between 1981 and 1990. C. parapsilosis was the most prevalent species between 1991 and 1995, causing 53 of 89 cases (60%). The mortality from C. albicans, 13 of 50 cases (26%), was significantly higher than the mortality from C. parapsilosis, 2 of 54 (4%) (P = 0.002; relative risk, 7; 95% confidence interval, 1.7 to 30). CONCLUSIONS: The rate of candidemia in our neonatal intensive care unit increased >11-fold in the 15 years from 1981 to 1995; the prevalent Candida species shifted from C. albicans to C. parapsilosis; and candidemia associated with C. albicans has significantly higher mortality than with C. parapsilosis.

Soluble tumor necrosis factor-alpha (TNF-alpha) receptors in human colostrum and milk bind to TNF-alpha and neutralize TNF-alpha bioactivity.

We used column chromatography, affinity binding, and bioassay methods to address whether the soluble tumor necrosis factor (TNF)-alpha receptors present in human colostrum and milk bind to and modify TNF-alpha bioactivity. In gel chromatography experiments, soluble TNF-alpha receptor I (sTNFRI) and sTNFRII in human colostrum sequentially increased their molecular sizes from 49 kD to 71 kD and 60 kD, respectively, after addition of increasing molar excesses of recombinant TNF-alpha. Application of colostrum to a TNF-alpha affinity matrix followed by washing and elution resulted in 2925-fold enrichment of sTNFRI, consistent with sTNFRI binding to the TNF-alpha affinity matrix. In other samples of colostrum and milk, the content of both sTNFRI and sTNFRII decreased significantly after passage over the matrix, but the material eluted from the matrix lost the ability to rebind to the TNF-alpha and was not active in a WEHI-13var bioassay for TNF-alpha. Specimens of human colostrum and milk diluted 1:16 shifted the LD50 for TNF-alpha 4-fold in this bioassay, and milk protection of WEHI-13var cells against TNF-alpha was significantly diminished after passage down the TNF-alpha affinity matrix (p < 0.001). Affinity purification of milk sTNFRI using polyclonal anti-sTNFRI produced fractions containing proteins of 30 kD, which could be visualized by Western blot using polyclonal anti-sTNFRI. Addition of this fraction to the WEHI-13var bioassay reversed the effects of 10 pg/mL TNF-alpha in the assay. These data demonstrate that sTNFRI and II from human colostrum and milk bind to TNF-alpha, that both colostrum and milk interfere with the bioactivity of TNF-alpha, and that affinity-purified sTNFRI from human milk blocks the bioactivity of TNF-alpha. These effects may contribute to the anti-inflammatory character of human colostrum and milk.

Type I cAMP-dependent protein kinase delays apoptosis in human neutrophils at a site upstream of caspase-3.

Current data suggest that apoptosis controls neutrophil numbers in tissues. We analyzed roles for and the sites of action for the cAMP-dependent protein kinases (cAPKs) in apoptosis induced in human neutrophils by in vitro storage, cycloheximide (CHX) exposure, and anti-Fas exposure. Treatment with 8-chlorophenylthio-cAMP (8-CPT-cAMP) prolonged the time required for 50% of the cells to exhibit apoptotic morphology (t50) from 16.3 to 41.8 h (in vitro culture), from 2.4 to 7.8 h (CHX), and from 4.8 to 6.5 h (anti-Fas). CHX +/- 8-CPT-cAMP did not significantly alter resting intracellular calcium levels and H-89, a selective inhibitor of cAPK, had no effect on apoptosis in the absence of the analogue. In contrast, site-selective cAMP analogues that specifically activated the type I cAPK, but not type II cAPK, synergistically attenuated apoptosis. Exposure to 8-CPT-cAMP delayed, in parallel, the activity of caspase-3 (CPP-32beta), whereas mitogen-activated protein kinase kinase (MAPKK) inhibitor, PD98059, had no effect on CHX-induced apoptosis +/- 8-CPT-cAMP. Together these results indicate that type I cAPK activation is necessary and sufficient to mediate cAMP-induced delay in human neutrophil apoptosis induced by several mechanisms and suggest that one of the major sites of cAPK action is upstream of caspase-3 (CPP-32beta) activation.

Antiinflammatory effects of human milk on chemically induced colitis in rats.

We examined the effects of a human milk diet on rats with chemical colitis induced with a 4% acetic acid enema. Colonic myeloperoxidase activity was used as a surrogate marker for neutrophil infiltration. Control rats fed rat chow had little colonic myeloperoxidase activity; geometric mean, 0.27 U/g of tissue. Rats with colitis fed rat chow had significantly increased colonic myeloperoxidase activity (geometric mean, 6.76 U/g, p < 0.01 versus no colitis), as did rats with colitis fed infant formula or Pedialyte (geometric mean, 6.92 and 8.13 U/g, respectively, both p < 0.01 versus no colitis). Animals with colitis fed human milk had significantly lower colonic myeloperoxidase activity (geometric mean, 2.34 U/g) than did animals with colitis fed either chow or infant formula (p < 0.001). Similar effects were seen in rats with colitis fed infant formula supplemented with recombinant human IL-1 receptor antagonist (geometric mean, 1.95 U/g). These data show that orally administered human milk has an antiinflammatory effect on chemically induced colitis in rats, which may be mediated in part by IL-1 receptor antagonist contained in human milk.

Soluble receptors and cytokine antagonists in human milk.

To determine whether human milk contained soluble receptors and cytokine antagonists that might contribute to its anti-inflammatory properties, ELISA and enzyme-amplified sensitivity immunoassay methods were used to quantitate soluble intercellular and vascular cell adhesion molecules, soluble E-selectin, soluble IL-6 receptor, IL-1 receptor antagonist, and soluble tumor necrosis factor-alpha (TNF-alpha) receptors I and II in human milk and colostrum. Soluble adhesion receptors (soluble intercellular and vascular cell adhesion molecules and soluble E-selectin) were present in colostrum at levels approximately equal to serum, whereas milk levels were significantly lower. Both colostrum and milk contained soluble IL-6 receptor, but the levels present were significantly lower than that reported for serum. The colostrum contents of IL-1 receptor antagonist (672 +/- 202 pg/mL), TNF-alpha receptor I (> 3703 +/- 305 pg/mL), and TNF-alpha receptor II (> 4507 +/- 770 pg/mL) were significantly elevated over serum/plasma levels. Milk levels of IL-1 receptor antagonist and TNF-alpha receptor I were also greater than serum/ plasma levels, but lower than colostrum levels. Examination of sequential milk specimens collected from seven women over a period of 2-6 mo showed that IL-1 receptor antagonist and TNF-alpha receptors I and II persisted throughout lactation. Column chromatographic fractionation of colostrum and milk demonstrated that soluble TNF-alpha receptors I and II had molecular sizes up to 60 kD, suggesting that they might be associated with other molecules. Antigen assays for TNF-alpha in colostrum and milk, as well as chromatographic fractionation experiments, showed that, although present, most TNF-alpha was not "free" in colostrum or milk, consistent with the observed content of soluble TNF-alpha receptors I and II. These studies demonstrate that human milk and colostrum contain soluble receptors and cytokine antagonists, materials which could contribute to their anti-inflammatory properties.

Inhibition of neutrophil function by human milk.

Human colostrum, the first product of lactation, has antioxidant properties and inhibits selected enzyme and bactericidal activities of human neutrophils. We examined the subsequent product of lactation, mature human milk, with respect to its antioxidant activities, its effects on neutrophil enzyme activities (myeloperoxidase, beta-glucuronidase, and lysozyme), and its effects on neutrophil bactericidal and phagocytic activities. Mature human milk displayed antioxidant characteristics similar to those of human colostrum, reducing cytochrome c and consuming H2O2. Mature milk also displayed colostrum-like characteristics in depressing neutrophil myeloperoxidase and beta-glucuronidase activities, but not in altering lysozyme activity. Neutrophil bactericidal activity against Staphylococcus aureus was depressed by both mature milk and colostrum, without dramatic effects on phagocytic activity. These data show that mature milk shares characteristics with human colostrum that may result in anti-inflammatory effects, but the magnitude of these effects is generally smaller.

In vivo biologic effects of PIXY321, a synthetic hybrid protein of recombinant human granulocyte-macrophage colony-stimulating factor and interleukin-3 in cancer patients with normal hematopoiesis: a phase I study.

PIXY321 is a novel fusion protein of recombinant human granulocyte-macrophage colony-stimulating factor and interleukin-3 that exhibits biologic effects of both its parent cytokines in vitro and in preclinical studies. To evaluate the clinical safety and hematopoietic effects of this hybrid cytokine, PIXY321 was administered by subcutaneous injection twice daily at doses of 25 to 1,000 micrograms/m2/day over 14 days to 24 patients with sarcoma before chemotherapy as part of a phase I trial. The treatment was associated with significant increases in white blood cell, neutrophil, platelet, and reticulocyte counts (all P < .001). The increase in neutrophil count was dose-related and was seen during treatment with the cytokine, whereas the increase in platelet count was gradual and peaked after the cessation of the cytokine treatment and was not clearly dose related. PIXY321 treatment also increased bone marrow (BM) cellularity and the percentage of BM cells in S phase (P < .001). In addition, there was a significant increase in the number of CD34+ cells and committed and multipotential progenitors in the peripheral blood. The ex vivo expansion capacity of peripheral blood and BM progenitor cells was preserved after the in vivo treatment with PIXY321. The treatment was well tolerated, with the most common side-effect being injection site reactions. The results of this study show the biologic and clinical activity of a genetically engineered fusion molecule of two hematopoietic cytokines in humans with normal hematopoietic function.

Immunocytochemical detection of lipid peroxidation in phagosomes of human neutrophils: correlation with expression of flavocytochrome b.

Oxidants generated by the NADPH oxidase of activated neutrophils can react with a number of tissue targets to form toxic metabolites such as 4-hydroxynonenal (4-HNE). 4-HNE is a lipid peroxidation product generated by free radical attack on omega-6 polyunsaturated fatty acids and is a marker for membrane lipid peroxidation. In this study, we examined the accumulation of 4-HNE-protein adducts in phagosomes of neutrophils obtained from a male patient with homozygous X-linked, flavocytochrome b-deficient chronic granulomatous disease (CGD), his heterozygous mother, and his normal father. Specific polyclonal antibodies recognizing 4-HNE-protein adducts and gp91-phox (flavocytochrome b large subunit) were prepared and used to immunocytochemically detect these antigens in cryofixed, molecular distillation-dried neutrophils. No 4-HNE-protein adducts were detected in flavocytochrome b-deficit cells from the homozygous patient or from the heterozygous CGD carrier. However, in gp91-phox-positive cells from both the normal and heterozygous CGD carrier, significant 4-HNE-protein adduct labeling was observed, primarily in the phagosomes. When data from single- and double-labeled cells were combined, the frequency distribution of the labels in phagosomes supported this observation, showing that neutrophils from the heterozygous CGD carrier were 71% 4-HNE-protein adduct-positive and 56% gp91-phox-positive, while cells from the normal father were > 97% positive for both 4-HNE-protein adducts and gp91-phox. These results confirmed the nitroblue tetrazolium tests of 100%, 60 +/- 2%, and 0% positive for the father's, mother's, and son's cells, respectively, and demonstrated that 4-HNE-protein adduct antibodies are useful and accurate probes of the occurrence of lipid peroxidation in vivo. We conclude that 4-HNE and resulting 4-HNE-protein adducts are generated as a result of NADPH oxidase activity in the phagosomes of human neutrophils and that these lipid peroxidation products may contribute to microbial killing and/or damage of neutrophil phagolysosomal proteins.

Human neutrophils store type II 14-kDa phospholipase A2 in granules and secrete active enzyme in response to soluble stimuli.

Although "secretory" type II 14-kDa phospholipase A2 (sPLA2) activity has been described in neutrophils, direct evidence of enzyme secretion has been elusive. We have used immunogold electron microscopy with polyclonal and monoclonal antibodies to sPLA2 to demonstrate localization of the enzyme to granules of resting human neutrophils and translocation to phagolysosomes. Soluble stimuli such as calcium ionophore A23187 stimulate loss of cell-associated enzymatic activity. Supernatant fluids from stimulated neutrophils lack measurable PLA2 but contain proteases which inactivate exogenous sPLA2. The use of alpha-1-antitrypsin as a protease inhibitor permitted this first demonstration of secretion of PLA2 activity from stimulated human neutrophils.