Published online November 12, 2007
doi:10.1084/jem.20071391
The Journal of Experimental Medicine, Vol. 204, No. 12, 2797-2802
The Rockefeller University Press, 0022-1007 $30.00
© 2007 Zhou et al.
Mast cell deficiency in KitW-sh mice does not impair antibody-mediated arthritis
Joseph S. Zhou,
Wei Xing,
Daniel S. Friend,
K. Frank Austen, and
Howard R. Katz
Department of Medicine, Harvard Medical School, and Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115
CORRESPONDENCE Howard R. Katz: hkatz{at}rics.bwh.harvard.edu
We previously reported that joint swelling, synovial thickening, and cartilage matrix depletion induced by the injection of anti-collagen monoclonal antibodies and lipopolysaccharide (LPS) in BALB/c mice are increased in the absence of inhibitory leukocyte immunoglobulin (Ig)-like receptor B4 (LILRB4; formerly gp49B1) in a neutrophil-dependent manner. Because both mast cells and neutrophils express LILRB4, we sought a mast cell requirement with mast cell–deficient mouse strains, but unexpectedly obtained full arthritis in KitW-sh mice and full resistance in KitW/KitW-v mice. KitW-sh mice were indeed mast cell deficient as assessed by histology and the absence of IgE/mast cell–dependent passive cutaneous anaphylaxis in the ear and joint as well as passive systemic anaphylaxis. Deletion of LILRB4 in KitW-sh mice exacerbated anti-collagen/LPS-induced joint swelling that was abolished by neutrophil depletion, establishing a counterregulatory role for LILRB4 in the absence of mast cells. Whereas blood neutrophil levels and LPS-elicited tissue neutrophilia were equal in KitW-sh and Kit+ mice, both were impaired in KitW/KitW-v mice. Although both strains are mast cell deficient and protected from IgE-mediated anaphylactic reactions, their dramatically different responses to autoantibody-mediated, neutrophil-dependent immune complex arthritis suggest that other host differences determine the extent of mast cell involvement. Thus, a conclusion for an absolute mast cell role in a pathobiologic process requires evidence from both strains.

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