Interleukin-8 is a major component of pleural liquid chemotactic activity in a rabbit model of endotoxin pleurisy.
Gram-negative endotoxin induces production of the potent chemotactic factor interleukin-8 (IL-8) in vitro; however, the importance of IL-8 in endotoxin-induced inflammation in vivo is unknown. We asked whether IL-8 is an important contributor to chemotactic activity in acute inflammatory liquids formed in response to endotoxin, and, if present, what concentrations of IL-8 antigen are generated. For these studies, we cloned and expressed rabbit recombinant IL-8 (rrIL-8), developed specific anti-rabbit IL-8 monoclonal antibodies (mAb), and then used these reagents to develop assays to detect rabbit IL-8 bioactivity and measure rabbit IL-8 antigen. Escherichia coli endotoxin (20 ng/ml, n = 4, or 2,000 ng/ml, n = 4) was instilled into the pleural space of eight rabbits for 6 h. Rabbit IL-8 bioactivity in the endotoxin pleurisy samples was assayed by measuring the migration of rabbit neutrophils toward the pleural liquid under two different conditions: 1) after addition of an anti-IL-8 neutralizing mAb and 2) after desensitization of the neutrophils to rrIL-8. Addition of the anti-IL-8 mAb decreased neutrophil migration toward the pleural liquid by 65 +/- 13 and 75 +/- 22% (mean +/- SE, after 20 and 2,000 ng/ml endotoxin, respectively; P < 0.01 compared with a control mAb). Desensitization of neutrophils to rrIL-8 decreased their migration toward the pleural liquid by 72 +/- 5% (P = 0.03, compared with exposure of neutrophils to buffer alone.(ABSTRACT TRUNCATED AT 250 WORDS)
Boylan
A M
AM
Department of Medicine and Lung Biology Center, San Francisco General Hospital, California.
Hébert
C A
CA
Sadick
M
M
Wong
W L
WL
Chuntharapai
A
A
Hoeffel
J M
JM
Hartiala
K T
KT
Broaddus
V C
VC
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D001826:Body Fluids / Q000378:metabolism*; D002630:Chemotactic Factors / Q000378:metabolism*; D004731:Endotoxins; D016209:Interleukin-8 / Q000378:metabolism*; D008297:Male; D015335:Molecular Probes / Q000235:genetics; D008969:Molecular Sequence Data; D010994:Pleura / Q000378:metabolism*; D010998:Pleurisy / Q000139:chemically induced / Q000378:metabolism*; D011817:Rabbits; D011994:Recombinant Proteins
D002630:Chemotactic Factors; D004731:Endotoxins; D016209:Interleukin-8; D015335:Molecular Probes; D011994:Recombinant Proteins