T. AkahoshiT. NagaokaR. NamaiN. Sekiyama

The effects of monosodium urate (MSU) crys- tals on apoptosis of cultured peripheral blood neutrophils were investigated. MSU crystals at low concentrations de- creased the rate of spontaneous apoptosis of neutrophils in a dose- and time-dependent manner. The culture superna- tant of MSU crystal stimulated neutrophils also promoted a delay in neutrophil apoptosis. MSU crystals at higher concentrations rapidly caused cell lysis. These findings in- dicated that MSU crystals are capable of amplifying the inflammatory responses of gouty arthritis by decreasing the rates of neutrophil apoptosis at lower concentrations and inducing cell lysis at higher concentrations.