Polymorphonuclear Leukocyte Responses to Monosodium Urate Crystals: Modification by Adsorbed Serum Proteins

The effects of protein absorption to monosodium urate monohydrate (MSU) crystals on crystal-induced lysosomal enzyme release from human neutrophils were studied. Native crystals produced prompt release of both lysosomal and cytoplasmic enzymes, suggesting that they are directly membranolytic for the neutrophil. When albumin, IgM, or beta-lactoglobulin were adsorbed to MSU crystals, lysis was blocked and lysosomal enzyme release was negligible. Prior incubation of crystals with 20% human serum or adsorption of IgG resulted in inhibition of lysis but enhancement of lysosomal enzyme liberation. This non-cytolytic lysosomal enzyme release induced by IgG-coated crystals may be important in the pathogenesis of acute gouty arthritis.