DEFECTIVE LYMPHOCYTE GLYCOSIDASES IN THE MACROPHAGE ACTIVATION CASCADE OF JUVENILE OSTEOPETROSIS

Generation of macrophage-activating factor requires a precursor protei n, Gc protein (serum vitamin D-3-binding protein), as well as particip ation of beta-galactosidase of inflammation-primed B lymphocytes and s ialidase of T lymphocytes. The treatment of human peripheral blood mon onuclear cells with an inflammatory lysophospholipid induced beta-gala ctosidase and sialidase activity of lymphocytes, leading to the genera tion of macrophage-activating factor and activation of monocytes/macro phages. However, lysophospholipid treatment of peripheral blood mononu clear cells from three infantile patients with osteopetrosis resulted in no significant activation of monocytes/macrophages. The lysophospho lipid-inducible beta-galactosidase activity of B lymphocytes as well a s that of the sialidase of T lymphocytes was found to be defective in these patients. (C) 1996 by The American Society of Hematology.