The Breakdown of Embryonic Cartilage and Bone Cultivated in the Presence of Complement-Sufficient Antiserum

Abstract

The action of anti-Forssman and anti-fowl-erythrocyte rabbit sera on the histology of cartilage and bone was described in Part 1 of this work. This present paper details the biochemical and enzymatic changes observed in chick limb-bone rudiments grown in organ culture in the presence of complement-sufficient antisera. Complement-sufficient antisera caused an extensive degradation of cartilage matrix, which was reflected in a 40% loss of hexosamine and a 25% loss of hydroxyproline, as compared with paired controls. On a DNA basis, no inhibition of synthesis of these compounds was apparent. The rate of extracellular liberation of lysosomal enzymes was greatest between 4 and 6 days in culture and depended upon the concentration of antiserum. The synthesis of lysosomal protease was much increased in the presence of complement-sufficient antiserum. Hydrocortisone (0.1 [mu]g/ml) inhibited the release of hexosamine and also decreased the release of lysosomal protease by 50%. Epsilon amino hexanoic acid (EAC), an inhibitor of lysosomal protease, was also effective in preventing the liberation of hexosamine and hydroxyproline by antisera. It appears that the interaction of complement-sufficient antiserum with the cell membrane produces indirectly a change in lysosomal physiology, leading to a specific extrusion from the cell of a proportion of its lysosomal enzymes. The mechanism of this release is discussed.