Platelet Activation and Reactivity in a Large Cohort of Patients with Gaucher Disease.

OBJECTIVES: Patients with Gaucher disease (GD) are at increased risk of bleeding and have varying degrees of thrombocytopenia, making the analysis of platelet function difficult. This study aimed to provide a clinically relevant quantitative assessment of platelet function and determine its relationship with bleeding and GD-related data. METHODS: Unstimulated and stimulated platelet function was measured by whole blood flow cytometry of platelet surface-activated αIIbß3 integrin (detected with monoclonal antibody PAC1), P-selectin (CD62P), and lysosomal-associated membrane protein (LAMP3/CD63) in 149 GD patients. RESULTS: GD patients had a higher level of unstimulated CD63 expression than healthy subjects, which was mildly correlated with glucosylsphingosine (lyso-Gb1) levels (r = 0.17, p-value = 0.042). Splenectomized GD patients had a higher level of unstimulated αIIbß3 integrin and P-selectin expression. Reduced platelet reactivity (-2 standard deviation of reference range) was found in 79 (53%, 95% confidence interval [CI]: 44-61%) patients, of whom 10 (6.7%, 95% CI: 3.3-12%) had more severe platelet dysfunction. In a multivariate model, only lyso-Gb1 levels were associated with the more severe platelet dysfunction. Fifty-four (49%) of 128 adult patients who completed the bleeding tendency questionnaire reported positive bleeding history. In a multivariate logistic model, older age (odds ratio [OR]: 1.05, 95% CI: 1.01-1.1) and low P-selectin reactivity (OR: 2.03, 95% CI: 1.25-3.35) were associated with more than one bleeding manifestation. CONCLUSION: Flow cytometry enables the study of platelet function in thrombocytopenic GD patients. A platelet degranulation defect, but not αIIbß3 integrin activation defect, is associated with clinical bleeding. In vivo increased CD63 expression may be related to GD-related inflammation.