A comparison of the effects of urate, hydroxyapatite and diamond crystals on polymorphonuclear cells: relationship of mediator release to the surface area and adsorptive capacity of different particles.

The ability of monosodium urate monohydrate (MSUM), hydroxyapatite and diamond crystals to stimulate phagocytosis, degranulation and secretion of cell movement factors (CMF) from polymorphonuclear leukocytes (PMN) was determined. The ability of each crystal to adsorb PMN derived enzymes and CMF was also compared. MSUM crystals stimulated greater enzyme release and generation of CMF than hydroxyapatite; in contrast, hydroxyapatite crystals exhibited greater adsorption of PMN products. This was partly due to the greater surface area (at a given concentration) of hydroxyapatite crystals. Diamond crystals clearly interacted with PMN, but they did not stimulate degranulation or CMF production.