Biomaterial Database

Inhibition of neutrophil oxidative burst and phagocytosis by meconium. 1995

P Clark, and P Duff

Division of Maternal-Fetal Medicine, University of Florida College of Medicine, Gainesville, USA.

OBJECTIVE Meconium in amniotic fluid has been associated with an increased prevalence of chorioamnionitis. In an effort to delineate the mechanism of this association, we determined the effect of meconium on the neutrophil's capacity for phagocytosis and microbial killing by oxidative burst in vitro. METHODS Sterile meconium samples were obtained from four fetuses at the time of breech delivery and were then pooled and lyophilized. Neutrophils were purified from whole blood of each of 13 pregnant nonlaboring patients. Phagocytosis and the oxidative burst of neutrophils in the presence and absence of meconium were assessed by single-cell analysis with flow cytometry. Phagocytosis was measured as the mean fluorescence intensity produced after 30 minutes of incubation with fluorescein-labeled Escherichia coli. Oxidative burst was measured as the mean fluorescence intensity resulting from the oxidation of internalized reduced dichlorodihydrofluorescein after 15 minutes of stimulation with phorbol myristate acetate. Oxidative burst was expressed as the neutrophil oxidative index and the net fluorescence intensity. Neutrophil oxidative index was equivalent to the quotient of the mean fluorescence intensity for phorbol myristate acetate-stimulated and unstimulated cells. Net fluorescence intensity was equivalent to the absolute difference between stimulated and unstimulated cells. RESULTS Exposure of neutrophils to light and very light meconium each resulted in significantly lower mean neutrophil oxidative index compared with unexposed controls (3.2 +/- 4.9 and 4.2 +/- 5.9 vs 16.2 +/- 7.5, p = 0.00002 and p = 0.0007, respectively) and significantly lower mean net fluorescence intensity than that of control cells (112 +/- 220 and 188 +/- 294 vs 613 +/- 328, p = 0.0001 and p = 0.005, respectively). Phagocytosis was significantly impaired in the presence of moderate meconium compared with control cells (2239 +/- 393 vs 4645 +/- 2071, p = 0.0001). Light meconium did not significantly affect phagocytosis. CONCLUSIONS Meconium has significant effects on neutrophil function in vitro. Both light and very light meconium inhibit the oxidative burst. Moderate meconium inhibits phagocytosis.

UI	MeSH Term	Description	Entries
D008470	Meconium	The thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the INTESTINAL GLANDS; BILE PIGMENTS; FATTY ACIDS; AMNIOTIC FLUID; and intrauterine debris. It constitutes the first stools passed by a newborn.	Meconiums
D009504	Neutrophils	Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes.	LE Cells,Leukocytes, Polymorphonuclear,Polymorphonuclear Leukocytes,Polymorphonuclear Neutrophils,Neutrophil Band Cells,Band Cell, Neutrophil,Cell, LE,LE Cell,Leukocyte, Polymorphonuclear,Neutrophil,Neutrophil Band Cell,Neutrophil, Polymorphonuclear,Polymorphonuclear Leukocyte,Polymorphonuclear Neutrophil
D010587	Phagocytosis	The engulfing and degradation of microorganisms; other cells that are dead, dying, or pathogenic; and foreign particles by phagocytic cells (PHAGOCYTES).	Phagocytoses
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D002821	Chorioamnionitis	INFLAMMATION of the placental membranes (CHORION; AMNION) and connected tissues such as fetal BLOOD VESSELS and UMBILICAL CORD. It is often associated with intrauterine ascending infections during PREGNANCY.	Amnionitis,Funisitis,Amnionitides,Chorioamnionitides,Funisitides
D005260	Female		Females
D005434	Flow Cytometry	Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake.	Cytofluorometry, Flow,Cytometry, Flow,Flow Microfluorimetry,Fluorescence-Activated Cell Sorting,Microfluorometry, Flow,Cell Sorting, Fluorescence-Activated,Cell Sortings, Fluorescence-Activated,Cytofluorometries, Flow,Cytometries, Flow,Flow Cytofluorometries,Flow Cytofluorometry,Flow Cytometries,Flow Microfluorometries,Flow Microfluorometry,Fluorescence Activated Cell Sorting,Fluorescence-Activated Cell Sortings,Microfluorimetry, Flow,Microfluorometries, Flow,Sorting, Fluorescence-Activated Cell,Sortings, Fluorescence-Activated Cell
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D016897	Respiratory Burst	A large increase in oxygen uptake by neutrophils and most types of tissue macrophages through activation of an NADPH-cytochrome b-dependent oxidase that reduces oxygen to a superoxide. Individuals with an inherited defect in which the oxidase that reduces oxygen to superoxide is decreased or absent (GRANULOMATOUS DISEASE, CHRONIC) often die as a result of recurrent bacterial infections.	Oxidative Burst,Burst, Oxidative,Burst, Respiratory,Bursts, Oxidative,Bursts, Respiratory,Oxidative Bursts,Respiratory Bursts