The Dysfunction of Platelets in Paroxysmal Nocturnal Hemoglobinuria

Introduction Thrombosis is one of the most dangerous complications in PNH, which can cause high mortality. However, its underlying mechanism remains unclear. To explore the mechanism of thrombosis in PNH, the function of platelets and complements were investigated in our study.

Material and Methods Serum level of terminal complement complex (sC5b-9) was detected by ELISA. The quantities of C5b-9,CD61 and CD62p on the membrane of platelets were detected by flow cytometry. Clinical tests were collected, including D-Dimer and platelet aggregation rates induced by adenosine diphosphate (ADP) and arachidonic acid (ARA).

Results The serum sC5b-9 level was significantly lower in the PNH/PNH-AA group than that in the control group (p<0.01). The deposition of C5b-9 on CD59- platelets (17.53%±6.27%) was higher than those on CD59+ platelets in PNH/PNH-AA patients(11.33%±5.03%) and normal controls(10.88%±3.58%) (p<0.01). D-dimer was significantly higher in PNH/PNH-AA patients (485ng/dL) than that in normal controls (311ng/dL)(p<0.05),especially in patients with LDH>1000U/L(789ng/dL). CD61 and CD62p expression on CD59+ platelets in PNH patients (76.87%,39.99%) were significantly lower than those in normal controls(98.41%,64.21%)(p<0.05,p<0.01).CD62p expression on CD59- platelets (40.07%) was significantly lower than normal controls(p<0.01). Platelet aggregation stimulated by agonists ADP (37.54±24.25)% and ARA (24.60%) were lower in the PNH/PNH-AA group than that in the control group(59.20±23.30)%, (14.54%) (p < 0.05). Interestingly,CD61 expression on CD59+ platelets in PNH patients was higher in the patients with higher type II PNH clone.

Conclusions The function of platelets was inversely inhibited,especially CD59+ platelets even if hypercoagulation continuously exists in PNH/PNH-AA.