Effect of a monocyte cell factor (MCF) on collagen production in cultured articular chondrocytes: role of prostaglandin E2.

A monocyte cell factor (MCF) inhibited the incorporation of (3H)proline into collagen of rabbit articular chondrocytes in culture, without significant effect on non-collagen protein. In addition, MCF produced a new compartmental repartition of collagen between cell layer and medium. No MCF-induced shift was observed in the relative proportion of collagens synthesized, type II remaining the major collagenous product. The inhibitory effect of MCF was not completely suppressed when prostaglandin synthesis was blocked by indomethacin. Addition of PGE2 at 12.5-25 micrograms/ml to the cultures resulted in a decrease of total collagen. Lower concentrations (0.42-0.85 microgram/ml) did not affect the total synthesis of collagen but changed its distribution between cells and medium in the same way as MCF. These results suggest that the MCF-stimulated release of PGE2 may be partially involved in the inhibitory effect observed on collagen synthesis.