Abstract
Mast cell-deficient mice are widely used to identify and quantify contributions of mast cells to diverse biological responses in vivo, including allergic inflammation. However, despite the fact that scores of genes have been identified as modifiers of allergic inflammation, most mast cell-deficient models have been available only on a single genetic background. We transferred the Kit(W-sh) allele onto the BALB/c background to generate BALB/c mast cell-deficient mice (BALB/c-Kit(W-sh/W-sh)). BALB/c-Kit(W-sh/W-sh) mice have dramatically reduced mast cell numbers (0-2% of wild type) in all tissues examined, as well as subtle hematologic differences from the corresponding wild type mice, including splenomegaly with evidence of increased splenic hematopoiesis. We examined in BALB/c-Kit(W-sh/W-sh) mice models of allergic inflammation that are substantially diminished in C57BL/6-Kit(W-sh/W-sh) mast cell-deficient mice. In a model of acute allergic inflammation, i.e., IgE-dependent passive cutaneous anaphylaxis, both ear swelling and leukocyte infiltration were largely or entirely absent in BALB/c-Kit(W-sh/W-sh) mice. In contrast, in two different models of allergic airway inflammation, airway hyperresponsiveness, lung inflammation, and airway remodeling developed robustly in mast cell-deficient BALB/c-Kit(W-sh/W-sh) mice. These results support the conclusion that the importance of mast cell contributions in various models of allergic inflammation may be at least partially determined by genetic background.