A defect in beta-galactosidase of B lymphocytes in the osteopetrotic (op/op) mouse.

Macrophages were activated by administration of an inflammatory lipid metabolite, lysophosphatidylcholine (lyso-Pc), to wild type mice but not osteopetrotic op/op mice. In vitro treatment of wild type mouse peritoneal cells with lyso-Pc efficiently activated macrophages whereas lyso-Pc-treatment of op/op mouse peritoneal cells resulted in no significant activation of macrophages. Generation of macrophage activating factor requires a precursor protein, serum vitamin D3-binding protein (DBP), as well as participation of beta-galactosidase of lyso-Pc-primed B lymphocytes. The treatment of wild type mouse peritoneal cells with lyso-Pc induced beta-galactosidase of B lymphocytes leading to the conversion of DBP to macrophage activating factor and subsequent activation of macrophages. The lyso-Pc-inducible beta-galactosidase activity of B lymphocytes was found to be defective in op/op mouse.