Soluble intercellular adhesion molecule-1 provokes polymorphonuclear leukocyte elastase release by CD18.
BACKGROUND
Elevated levels of soluble intercellular adhesion molecule-1 (sICAM-1) correlate with the development of postinjury multiple organ failure. Soluble ICAM-1 secretion is known to be induced in endothelial cells and monocytes by diverse inflammatory stimuli. We have found that incubation of quiescent polymorphonuclear leukocytes (PMNs) with sICAM-1 elicits elastase release and, more recently, that cross-linking CD18 receptors on PMNs also produces elastase release. Consequently, our study hypothesis was that sICAM-1 provokes PMN elastase release through its interaction with CD18.


METHODS
To obtain sICAM-1, Chinese hamster ovarian cells transfected with human ICAM-1 were lysed and centrifuged at 150,000 g for 1 hour; the supernatant was passed over an ICAM-1 affinity column, eluted with 0.1 mmol/L glycine HCl, and concentrated with dialysis filter. Human PMNs (2.5 x 10(5)) were saturated with specific monoclonal antibodies for the beta 2 subunits (CD11a, CD11b, CD18) or nonspecific monoclonal antibodies for 30 minutes on ice before a 1-hour incubation with sICAM-1 (75 ng/ml) at 37 degrees C. Elastase activity was measured by the cleavage of n-methoxysuccinyl-A-A-P-V-p-nitroanilide.


RESULTS
Neutrophil incubation with sICAM-1 resulted in 19.2% +/- 2.8% of total PMN elastase, compared with 2.4% +/- 0.5% in the controls. Blockade of CD18 abrogated sICAM-1 provoked elastase release with monoclonal antibodies to CD18 (TS1/18, 31H8) resulting in 4.3% +/- 1.0% and 5.5% +/- 1.4% elastase release, respectively. Blockade of CD11a, CD11b, and nonspecific antibody controls had no effect on sICAM-1 induced elastase release.


CONCLUSIONS
In vitro, sICAM-1 provokes PMN elastase release through CD18. This may represent a mechanism by which elevated levels of circulating sICAM-1, released from local injury sites, provoke distal organ dysfunction.
Barnett
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Department of Surgery, Denver General Hospital, Colo.
Moore
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Moore
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Biffl
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Partrick
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DA
D000818:Animals; D000911:Antibodies, Monoclonal; D001667:Binding, Competitive / Q000276:immunology; D018845:CD11 Antigens / Q000276:immunology; D018821:CD18 Antigens / Q000494:pharmacology*; D016466:CHO Cells / Q000502:physiology; D006224:Cricetinae; D005434:Flow Cytometry; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000276:immunology / Q000502:physiology*; D019272:Leukocyte Elastase; D010196:Pancreatic Elastase / Q000378:metabolism*; D012995:Solubility; D014162:Transfection
D000911:Antibodies, Monoclonal; D018845:CD11 Antigens; D018821:CD18 Antigens; D018799:Intercellular Adhesion Molecule-1; D010196:Pancreatic Elastase; D019272:Leukocyte Elastase