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Blood, 18 June 2009, Vol. 113, No. 25, pp. 6485-6494.
Prepublished online as a Blood First Edition Paper on April 21, 2009; DOI 10.1182/blood-2008-12-192617.
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VASCULAR BIOLOGY
Antimyeloperoxidase antibodies rapidly induce 4-integrin–dependent glomerular neutrophil adhesion
Michael P. Kuligowski1,
Rain Y. Q. Kwan1,
Cecilia Lo1,
Cyndi Wong1,
Will G. James1,
Dorothee Bourges1,
Joshua D. Ooi1,
Latasha D. Abeynaike1,
Pam Hall1,
A. Richard Kitching1,2, and
Michael J. Hickey1
1 Centre for Inflammatory Diseases, Monash University Department of Medicine, and
2 Department of Nephrology and Pediatric Nephrology, Monash Medical Centre, Clayton, Australia
Patients with antineutrophil cytoplasmic antibodies (ANCAs) frequently develop severe vasculitis and glomerulonephritis. Although ANCAs, particularly antimyeloperoxidase (anti-MPO), have been shown to promote leukocyte adhesion in postcapillary venules, their ability to promote adhesion in the glomerular vasculature is less clear. We used intravital microscopy to examine glomerular leukocyte adhesion induced by anti-MPO. In mice pretreated with LPS, 50 µg anti-MPO induced LFA-1–dependent adhesion in glomeruli. In concert with this finding, in mice pretreated with LPS, more than 80% of circulating neutrophils bound anti-MPO within 5 minutes of intravenous administration. However, even in the absence of LPS, more than 40% of circulating neutrophils bound anti-MPO in vivo, a response not seen in MPO–/– mice. In addition, a higher dose of anti-MPO (200 µg) induced robust glomerular leukocyte adhesion in the absence of LPS. The latter response was β2-integrin independent, instead requiring the 4-integrin, which was up-regulated on neutrophils in response to anti-MPO. These data indicate that anti-MPO antibodies bind to circulating neutrophils, and can induce glomerular leukocyte adhesion via multiple pathways. Lower doses induce adhesion only after an infection-related stimulus, whereas higher doses are capable of inducing responses in the absence of an additional inflammatory stimulus, via alternative adhesion mechanisms.

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