Interactions of murine macrophages with monosodium urate crystals: stimulation of lysosomal enzyme release and prostaglandin synthesis.

Exposure of murine peritoneal macrophages to crystals of monosodium urate monohydrate (MSUM) stimulated release of inflammatory mediators from the cells. There was an early, rapid burst of prostaglandin E2 (PGE2) synthesis which was complete by 2 h. Release of N-acetyl glucosaminidase (NAG), a lysosomal enzyme, was evident within 1 h and was maximal by 8 h. Early release of lysosomal enzymes (1-2 h) was not accompanied by leakage of cytoplasmic enzymes; however, treatment with high concentrations of MSUM, or prolonged exposure to crystals, provoked release of the cytoplasmic enzyme lactate dehydrogenase, presumably as a result os cell lysis. Responses of macrophages to MSUM occurred in the absence of serum but were modified by serum proteins. Prior exposure of crystals to IgG potentiated release of NAG and PGE2. Exposure to albumin slightly enhanced release of PGE2 induced by MSUM but did not affect NAG release. However, albumin prevented enhancement of NAG release by IgG. The interaction of MSUM with macrophages, and subsequent release of inflammatory mediators, may contribute to the inflammation association with both acute and chronic gouty arthritis.