Studies were carried out to demonstrate residual chymopapain activity in
intervertebral discs after chemonucleolysis; protease assay, enzyme-linked
immunosorbent assay, and immunohistochemical localization of the
chymopapain in the disc tissue were done. Chymopapain, one milligram per
level, was injected into the normal lumbar intervertebral discs of adult
mongrel dogs and the discs were excised after two weeks. Proteolytically
active chymopapain was still present in the extract of intervertebral disc
at this time. The proteolytic activity was decreased by sulfhydryl
inhibitors but not by inhibitors of metalloproteases or serine proteases.
Protease and enzyme-linked immunosorbent assays showed that 0.60 +/- 0.48
per cent and 0.49 +/- 0.38 per cent of the original dose was present two
weeks after the injection. Chymopapain was shown by immunohistochemical
staining to be diffusely located throughout the extracellular matrix of the
anulus fibrosus and the nucleus pulposus. Some cells, located mainly in the
inner portion of the anulus, contained vacuoles filled with immunoreactive
product.