Intracellular enzymes and kinin enzymes in synovial fluid in joint diseases. Origin and relation to disease category.

In the present investigation we have studied changes in the synovial fluid obtained from inflammatory and non-inflammatory joints, not only of lysosomal enzymes, but of five intracellular enzymes selected to represent different intracellular compartments. Although the study has not revealed a characteristic composition of the synovial fluid for any of the diseases studied, it has indicated that, in the rheumatic diseases, the release of lysosomal enzymes is accompanied by the release of other intracellular enzymes. This suggests that the presence of lysosomal enzymes in the synovial fluid is the result of an overall change in cell permeability or of cell death rather than due to any specific change in the lysosomes.