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J. Exp. Med.,
Volume 186, Number 11, December 1, 1997 1853-1863
Receptor-dependent
Neutrophil Adhesion and Complement-dependent
Proteinuria in Acute Glomerulonephritis
By


From the * Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts 02115; Mac-1 (
Center for Blood Research and § Department of Pathology, Harvard Medical School, Boston,
Massachusetts 02115; and
University Hospital Nijmegen, 6500 HB Nijmegen, The Netherlands
m
2), a leukocyte adhesion receptor, has been shown in vitro to functionally interact
with Fc
receptors to facilitate immune complex (IC)-stimulated polymorphonuclear neutrophil (PMN) functions. To investigate the relevance of Mac-1-Fc
R interactions in IC-mediated injury in vivo, we induced a model of Fc-dependent anti-glomerular basement membrane
(GBM) nephritis in wild-type and Mac-1-deficient mice by the intravenous injection of anti-GBM antibody. The initial glomerular PMN accumulation was equivalent in Mac-1 null and
wild-type mice, but thereafter increased in wild-type and decreased in mutant mice. The absence of Mac-1 interactions with obvious ligands, intercellular adhesion molecule 1 (ICAM-1), and C3 complement, is not responsible for the decrease in neutrophil accumulation in Mac-1-
deficient mice since glomerular PMN accumulation in mice deficient in these ligands was
comparable to those in wild-type mice. In vitro studies showed that spreading of Mac-1-null PMNs to IC-coated dishes was equivalent to that of wild-type PMNs at 5-12 min but was
markedly reduced thereafter, and was associated with an inability of mutant neutrophils to redistribute filamentous actin. This suggests that in vivo, Mac-1 is not required for the initiation
of Fc-mediated PMN recruitment but that Mac-1-Fc
R interactions are required for filamentous actin reorganization leading to sustained PMN adhesion, and this represents the first demonstration of the relevance of Mac-1-Fc
R interactions in vivo. PMN-dependent proteinuria,
maximal in wild-type mice at 8 h, was absent in Mac-1 mutant mice at all time points. Complement C3-deficient mice also had significantly decreased proteinuria compared to wild-type
mice. Since Mac-1 on PMNs is the principal ligand for ic3b, an absence of Mac-1 interaction
with C3 probably contributed to the abrogation of proteinuria in Mac-1-null mice.
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