BACKGROUND: Racial differences in coagulation are poorly understood. While some studies suggest a 'prothrombotic' coagulation profile in blacks compared with whites, others report an increased bleeding risk for blacks in various clinical settings. Moreover, preclinical data suggest a link between the Duffy antigen (=DARC, Duffy antigen receptor of chemokines) and coagulation. OBJECTIVES: Based on our previous research in Duffy antigen negative Africans, we hypothesized that Africans have an attenuated procoagulant response compared with Caucasians in a model of lipopolysaccharide (LPS)-induced, tissue factor (TF)-triggered coagulation activation. PATIENTS/ METHODS: Healthy male volunteers (16 Duffy-negative Africans, 16 Duffy-positive Caucasians) received 2 ng kg(-1) LPS, and outcome parameters were measured using enzyme immunoassays and real-time polymerase chain reaction (RT-PCR, Taqman). RESULTS: LPS increased microparticle (MP)-associated TF procoagulant activity (PCA) less in Africans than Caucasians. Africans had reduced in vivo thrombin formation compared with Caucasians: they generated less thrombin-antithrombin (TAT) complexes (10.4 pg mL(-1) vs. 23.0 pg mL(-1), P<0.0001) and less prothrombin fragments (F1+2) (337 pmol mL(-1) vs. 819 pmol mL(-1), P<0.0001). Consistently, Africans also had decreased fibrin formation (D-dimer: 0.3 pg mL(-1) vs. 0.5 pg mL(-1), P=0.02). CONCLUSION: Duffy-negative subjects of African descent have a markedly reduced procoagulant response in a model of LPS-induced, TF-triggered coagulation activation compared with Duffy-positive healthy Caucasians.
BACKGROUND: Racial differences in coagulation are poorly understood. While some studies suggest a 'prothrombotic' coagulation profile in blacks compared with whites, others report an increased bleeding risk for blacks in various clinical settings. Moreover, preclinical data suggest a link between the Duffy antigen (=DARC, Duffy antigen receptor of chemokines) and coagulation. OBJECTIVES: Based on our previous research in Duffy antigen negative Africans, we hypothesized that Africans have an attenuated procoagulant response compared with Caucasians in a model of lipopolysaccharide (LPS)-induced, tissue factor (TF)-triggered coagulation activation. PATIENTS/ METHODS: Healthy male volunteers (16 Duffy-negative Africans, 16 Duffy-positive Caucasians) received 2 ng kg(-1) LPS, and outcome parameters were measured using enzyme immunoassays and real-time polymerase chain reaction (RT-PCR, Taqman). RESULTS:LPS increased microparticle (MP)-associated TF procoagulant activity (PCA) less in Africans than Caucasians. Africans had reduced in vivo thrombin formation compared with Caucasians: they generated less thrombin-antithrombin (TAT) complexes (10.4 pg mL(-1) vs. 23.0 pg mL(-1), P<0.0001) and less prothrombin fragments (F1+2) (337 pmol mL(-1) vs. 819 pmol mL(-1), P<0.0001). Consistently, Africans also had decreased fibrin formation (D-dimer: 0.3 pg mL(-1) vs. 0.5 pg mL(-1), P=0.02). CONCLUSION: Duffy-negative subjects of African descent have a markedly reduced procoagulant response in a model of LPS-induced, TF-triggered coagulation activation compared with Duffy-positive healthy Caucasians.
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