Neutrophil adhesion molecule expression in the developing neonatal rat exposed to hyperoxia.
Neonatal rats have an increased tolerance to hyperoxia, which is associated with a diminished pulmonary inflammatory response compared with adults. To investigate this differing response, expression of the neutrophil adhesion molecules, L-selectin and CD18, and levels of soluble L-selectin, were examined using flow cytometry and sandwich enzyme-linked immunosorbent assay on air-exposed neonatal rat neutrophils at 0-24 and 72 h and 7, 10, 14, and 21 d of age compared with the adult and after exposure to hyperoxia (>/= 98% O2) for 56 h in adults and for 72 h and 7 d in neonates. Expression of L-selectin in 0-24-h neonates was similar to adults, but was significantly lower than adults at 72 h and 7 d (P = 0.011). Soluble L-selectin levels were significantly higher than those in adults in the 0-24- and 72-h neonates (P < 0.001). CD18 expression in unstimulated and activated neutrophils of neonatal rats was higher at 0-24 h than in the adult (P < 0.001), but thereafter did not differ from adults. After hyperoxic exposure, L-selectin did not differ between the exposure groups but soluble L-selectin tended to increase in neonates after 7 d of O2 exposure Finally, CD18 was significantly higher after hyperoxic exposure of the adult (P = 0.008), but did not change with oxygen exposure in the neonate. Based on these findings, we speculate that differences between neonatal and adult rats in expression of L-selectin may contribute to delayed oxygen toxicity in neonatal rats.
Department of Pediatrics, Route 0526, University of Texas Medical Branch, Galveston, TX 77555-0526, USA. skeeney@utmb.edu
Susan M
SM
Gerik
Susan E
SE
Keeney
Dara V
DV
Dallas
Kimberly H
KH
Palkowetz
Frank C
FC
Schmalstieg
D000375:Aging / Q000276:immunology; D000818:Animals; D000831:Animals, Newborn; D018821:CD18 Antigens / Q000276:immunology / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000096:biosynthesis*; D002634:Chemotaxis, Leukocyte / Q000276:immunology; D004198:Disease Susceptibility / Q000276:immunology; D005260:Female; D018496:Hyperoxia / Q000097:blood / Q000276:immunology* / Q000503:physiopathology; D019041:L-Selectin / Q000097:blood* / Q000276:immunology; D008168:Lung / Q000254:growth & development / Q000276:immunology* / Q000503:physiopathology; D008297:Male; D009504:Neutrophils / Q000276:immunology*; D010100:Oxygen / Q000633:toxicity; D011014:Pneumonia / Q000139:chemically induced / Q000276:immunology / Q000503:physiopathology; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley
D018821:CD18 Antigens; D015815:Cell Adhesion Molecules; D019041:L-Selectin; D010100:Oxygen