Accelerated fluid endocytosis and re-exocytosis by lysosomal storage disease fibroblasts.

Fluid-phase endocytosis was significantly faster in three lines of human lysosomal storage disease fibroblasts (two I cells and one Sandhoff's) than in three normals. Re-exocytosis of fluid showed similar kinetics in all lines when release was expressed as a percentage of the radioactivity associated with the cells at the commencement of the measurement. This indicates a greater absolute exocytosis of radioactive sucrose from the storage disease cells. The data imply that the interactions of lysosomes with other cellular membranes are perturbed in the storage diseases.