Chondrocyte activation by a putative interleukin-1 derived from lapine polymorphonuclear leukocytes.

Polymorphonuclear leukocytes (PMNs) recovered from 4-h lapine peritoneal exudates contained factors which provoked the synthesis of collagenase, gelatinase, caseinase, and prostaglandin E2 by lapine articular chondrocytes. Rapid secretion of these factors occurred after exposing the polymorphs to phorbol myristate acetate or formyl-Met-Leu-Phe. Fractionation of polymorph lysates by HPLC size exclusion chromatography provided a molecular weight of approximately 14,000 for the active principle. Examination of the most active fraction by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by silver staining, confirmed the presence of a single band with this apparent molecular weight. Isoelectric focusing of this fraction revealed the presence of four distinct bands with the pI values 6.90, 7.05, 7.45, and 7.55. This fraction tested positive in a bioassay for interleukin-1. We were unable to activate chondrocytes by exposure to extracts of human PMNs from either peripheral blood or inflammatory synovial fluid.