Heterogeneity in F-actin polymerization of cord blood polymorphonuclear leukocytes stimulated by N-formyl-methionyl-leucyl-phenylalanine.
BACKGROUND
To elucidate the mechanism responsible for defects of polymorphonuclear leukocyte (PMNL) chemotaxis of neonates, we determined actin polymerization of NBD (7-nitrobenz-2-oxa-diazol)-phallacidin-stained PMNL following stimulation with either N-formyl-methionyl-leucyl-phenylalanine (fMLP) or phorbol myristate acetate (PMA) in cord blood and adult controls.


METHODS
We measured F-actin content in PMNL stained with NBD-phallacidin using flow cytometry.


RESULTS
Relative F-actin polymerization, that is, a ratio of stimulated F-actin to basal F-actin, was significantly decreased in cord blood PMNL when compared with that of adult PMNL. Distribution of fMLP-stimulated F-actin showed a bimodal pattern, while adult PMNL disclosed a single pattern. Following stimulation with PMA, however, F-actin levels were equal in both cord and adult PMNL. A fluorescein isothiocyanate-conjugated fMLP receptor assay showed no significant difference in binding capacity of fMLP receptors between adult and cord PMNL.


CONCLUSIONS
These results indicate that a deficiency of PMNL chemotaxis in neonates may be due, in part, to decreased relative F-actin polymerization, which may be caused by functional heterogeneity in cord blood PMNL.
Taniuchi
S
S
Department of Pediatrics Kansai Medical University, Osaka, Japan. taniuchi@takii.kmu.ac.jp
Kinoshita
Y
Y
Yamamoto
A
A
Fujiwara
T
T
Hattori
K
K
Hasui
M
M
Kobayashi
Y
Y
D000199:Actins / Q000032:analysis* / Q000276:immunology*; D000328:Adult; D000367:Age Factors; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000276:immunology*; D005260:Female; D005312:Fetal Blood / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D007231:Infant, Newborn / Q000097:blood* / Q000276:immunology*; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000737:chemistry* / Q000187:drug effects / Q000276:immunology*; D011108:Polymers; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000199:Actins; D011108:Polymers; D009240:N-Formylmethionine Leucyl-Phenylalanine; D013755:Tetradecanoylphorbol Acetate