Choroidal blastomycosis. A report of two cases

Isolated resting platelets are able to limit neutrophil activation and then can control the tissue-damaging potential of activated neutrophils. In the present study, platelet-neutrophil interactions have been evaluated in 10 uremic patients; the blood samples have been collected before the hemodialysis session. Twelve normal subjects served as controls. Platelets and neutrophils have been isolated and recombined in an autologous ex vivo system. Anion superoxide production and chemiluminescence (which is related to hypochlorous acid production) have been evaluated after stimulation with N-formyl-methionyl-leucyl-phenylalanine. Coincubation of platelets from normal subjects with autologous neutrophils led to a dose-dependent inhibition of both superoxide anion generation induced by N-formyl-methionyl-leucyl-phenylalanine and chemiluminescence. Instead, platelets from uremic patients have not affected superoxide anion production by autologous neutrophils. The chemiluminescence was reduced by coincubation with autologous platelets only at the highest platelet-neutrophil ratio (100:1). In conclusion, the modulation exerted by platelets towards neutrophil activation can be impaired in chronic uremia. Therefore, the tissue-damaging potential of circulating neutrophils, due to toxicity by superoxide anion and hypochlorous acid, may be increased.