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1.
Scand J Immunol ; 85(5): 365-371, 2017 May.
Article in English | MEDLINE | ID: mdl-28199745

ABSTRACT

Neutrophil migration and respiratory burst are the prerequisite for efficient first line defense against invading microorganisms. However, migration and respiratory burst can be compromised in adults and especially in newborn infants, where sustained neutrophil accumulation, uncontrolled burst and reduced scavenging of ROS might cause inadvertent tissue damage due to uncontrolled inflammation. The aim of this study was to investigate the modulatory effect of the chemoattractants formyl-methionyl-leucyl-phenylalanine (fMLP) and IL-8 on respiratory burst in neutrophils from term newborn infants and adults. Whole blood from the umbilical cord of 17 healthy term newborn infants delivered by caesarean section and from 17 healthy adults as reference was preincubated with fMLP or IL-8 and stimulated with PMA or Escherichia coli bacteria. Respiratory burst was quantified by flow cytometry analysis of dihydrorhodamine 123 fluorescence. fMLP reduced the PMA-induced respiratory burst of neutrophils from newborn infants and adults by 12% and 21%, respectively (P < 0.05). E. coli-induced burst was also reduced by fMLP in neutrophils from newborn infants (10%; P < 0.01) and adults (6%; P < 0.05). No such changes were observed with IL-8. Similar respiratory burst in response to single stimulus with PMA or E. coli was observed in both newborn infants and adults. fMLP reduced PMA- and E. coli-induced respiratory burst of neutrophils in whole blood from term newborn infants as well as in adults. The reduced respiratory burst by fMLP might be a mechanism to reduce the detrimental effects of uncontrolled inflammation during neutrophil migration.


Subject(s)
Escherichia coli/growth & development , N-Formylmethionine Leucyl-Phenylalanine/pharmacology , Neutrophils/drug effects , Respiratory Burst/drug effects , Tetradecanoylphorbol Acetate/pharmacology , Adolescent , Adult , Aged , Dose-Response Relationship, Drug , Escherichia coli/physiology , Flow Cytometry , Humans , Infant, Newborn , Interleukin-8/pharmacology , Middle Aged , Neutrophils/metabolism , Neutrophils/microbiology , Young Adult
2.
Scand J Immunol ; 84(6): 332-337, 2016 Dec.
Article in English | MEDLINE | ID: mdl-27606963

ABSTRACT

We have previously observed that neutrophils from neonates exhibit different migratory responses to intermediate and end-target chemoattractants compared to adults. The aim of this study was to investigate the effect of the chemoattractants IL-8 (intermediate) and formyl-methionyl-leucyl-phenylalanine (fMLP; end-target) on cell surface receptor expression involved in adhesion, migration and granule release of neutrophils from term newborn infants and adults. Heparinized cord blood from 16 healthy term newborn infants delivered by caesarean section and peripheral blood from 17 healthy adults were incubated with 1 µm IL-8 or 0.1 µm fMLP, previously defined as optimal inducers of neutrophil migration. The leukocytes were labelled with antibodies to cell surface receptors (CD11b, CD15S, CD18, CD35, CD44, CD64, CD65, CD88, CD162, CD181 and CD182). Receptor expression was quantified by flow cytometry analysis. Upregulation of CD11b and downregulation of CD88 and CD182 after stimulation with IL-8 were more pronounced in adults than in neonates (P < 0.05, P < 0.05 and P ≤ 0.001, respectively), whereas fMLP induced changes in receptor expression that were of the same magnitude in neutrophils from neonates as from adults. We observed similar expression of receptors that mediate adhesion, migration, granule activation and phagocytosis induced by fMLP in neutrophils from neonates and adults. In contrast, differences between neonates and adults, induced by IL-8, suggest that the neutrophil response to intermediate chemoattractants might lead to a compromised infectious response in newborn infants.


Subject(s)
CD11b Antigen/metabolism , Neutrophils/metabolism , Receptor, Anaphylatoxin C5a/metabolism , Receptors, Interleukin-8B/metabolism , Adolescent , Adult , Aged , Cell Adhesion , Cell Degranulation , Cell Movement , Cells, Cultured , Humans , Infant, Newborn , Interleukin-8/immunology , Middle Aged , N-Formylmethionine Leucyl-Phenylalanine/immunology , Neutrophils/immunology , Phagocytosis , Young Adult
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