Variation in the effects of mononuclear cell products from different individuals on metalloproteinase secretion from human articular cartilage

Abstract

Human articular cartilage in organ culture shows a variable degree of endogenous metalloproteinase secretion depending on the individual from whom it was obtained. Cartilage with low endogenous levels are stimulated by interleukin 1 (IL-1) to levels comparable to the high endogenous group. Total blood mononuclear cell products obtained from different individuals either behave in a manner similar to that seen with IL-1, which results in sustained high levels of enzyme secretion, or show an initial stimulation followed by a subsequent dropoff in enzyme secretion even though incubation is continued in the presence of mononuclear cell products. The factor(s) causing this dropoff can be distinguished from IL-1. Production and regulation of such factors may reflect a mechanism whereby the action of IL-1 can be controlled during the inflammatory response.