A DEFECT IN INDUCIBLE BETA-GALACTOSIDASE OF B-LYMPHOCYTES IN THE OSTEOPETROTIC (MI MI) MOUSE/

Macrophages were activated by administration of an inflammatory lipid metabolite, lysophosphatidylcholine (lyso-Pc), to wild type mice but n ot murine (microphthalmic) osteopetrotic (mi/mi) mutant mice. In vitro treatment of wild type mouse peritoneal cells with lyso-Pc efficientl y activated macrophages whereas lyso-Pc-treatment of mi mutant mouse p eritoneal cells resulted in no activation of macrophages. Generation o f macrophage activating factor requires a precursor protein, serum vit amin D binding protein (DBP), and participation of lyso-Pc-inducible b eta-galactosidase of B lymphocytes. Lyso-Pc-inducible beta-galactosida se of B lymphocytes was found to be defective in mi mutant mice.