Expression and regulation of L-selectin on eosinophils from human adults and neonates.
L-Selectin, previously known as LEC.CAM-1, LECAM-1, LAM1, and as the MEL-14, Leu-8, TQ1, and DREG-56 antigens, is a leukocyte membrane protein that participates in adhesion to endothelium. We studied its expression on eosinophils using flow cytometry and the MAb Dreg-56 and Leu-8. Unstimulated peripheral blood eosinophils from healthy adults expressed about one third the level of L-selectin as neutrophils (mean +/- SD specific fluorescence: 20.9 +/- 3.2 versus 54.5 +/- 8.4, p = 0.0001, n = 18). After stimulation with A23187, L-selectin expression on eosinophils was rapidly lost. This was temporally correlated with increased expression of Mac-1 (CD11b/CD18); the kinetics on eosinophils and neutrophils were similar. Eosinophil expression of L-selectin decreased modestly after stimulation with platelet activating factor, but was minimally affected by N-formyl-methionyl-leucyl-phenylalanine, leukotriene B4, or C5a compared with their effects on neutrophils. Eosinophils from cord blood of healthy neonates born at term expressed less L-selectin than adult eosinophils (10.4 +/- 3.8 versus 19.4 +/- 2.7, p = 0.0001, n = 9); the relative reduction was the same as on cord blood neutrophils (36.4 +/- 8.2 versus 55.5 +/- 4.8, p = 0.0001, n = 9). Relative to baseline expression, the responses of neonatal and adult cells to stimulation did not differ. We conclude that neonatal eosinophils have abnormalities in L-selectin expression similar to neonatal neutrophils and suggest that decreased expression of L-selectin and a diminished responsiveness to direct stimulation with chemotactic factors are possible mechanisms that may limit the exudation of eosinophils.
D000328:Adult; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000097:blood*; D002630:Chemotactic Factors / Q000494:pharmacology; D015536:Down-Regulation; D004804:Eosinophils / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D005312:Fetal Blood / Q000166:cytology / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007231:Infant, Newborn; D007700:Kinetics; D019041:L-Selectin; D008562:Membrane Glycoproteins / Q000097:blood*
D015815:Cell Adhesion Molecules; D002630:Chemotactic Factors; D008562:Membrane Glycoproteins; D019041:L-Selectin