Lysosomal activation by neutral saccharides in cell cultures of synovium.

On exposure to sucrose or neutral polysaccharides, cell cultures from human synovium showed cytoplasmic vacuolation, increased numbers of lysosomes, and ultrastructural changes simulating those described in rheumatoid synovial intima and similarly treated embryonic caritlage and bone. These changes were accompanied by raised intracellular lysosomal enzyme activity without corresponding increases in the extracellular level of these enzymes. Structural changes and enzymic responses were less intense during exposure to the neutral polysaccharides. The secretion of large polymers of hyaluronic acid was consistently decreased during sucrose treatment. Evidence of heightened hyaluronidase-like activity was found in cellular extracts of sucrose-treated cultures, but not in the culture medium.