SECRETORY LEUKOCYTE PROTEINASE-INHIBITOR IS PRODUCED BY HUMAN ARTICULAR-CARTILAGE CHONDROCYTES AND INTERVERTEBRAL DISC FIBROCHONDROCYTES

The objective of this study was to examine the expression of the secre tory leucocyte proteinase inhibitor (SLPI) gene by human articular car tilage chondrocytes and intervertebral disc fibrochondrocytes. RNA was extracted from human articular cartilage chondrocytes, synovial fibro blasts and fibrochondrocytes of the annulus fibrosus. Expression was a nalysed by Northern blotting and hybridisation to a SLPI RNA probe. SL PI was isolated from chondrocyte culture supernatant by gel-permeation and cation-exchange chromatography and examined by a solid-phase enzy me-linked immunofiltration assay for SLPI and by SDS/PAGE using Wester n blotting with polyclonal IgG samples against bronchial mucus leucocy te proteinase inhibitor and SLPI. This identified biochemically and im munologically the major serine proteinase inhibitory protein synthesis ed by chondrocytes as SLPI. Secretory leucocyte proteinase inhibitor m RNA was detected in RNA preparations from articular cartilage chondroc ytes and annulus fibrosus fibrochondrocytes. The results presented her e allowed us to deduce that human articular cartilage chondrocytes and intervertebral disc fibrochondrocytes synthesized SLPI whereas human synovial fibroblasts did not.