Prompt diagnostic work-up of suspected heparin-induced thrombocytopenia (HIT) is critical for guiding initial patient management. We assessed the performance of three immunoassays detecting anti-PF4/heparin-antibodies, derived a diagnostic algorithm with a short analytical turnaround-time (TAT) and prospectively validated it. Plasma samples were analysed by Zymutest-HIA-IgG, HemosIL-AcuStar-HIT-IgG and ID-H/PF4-PaGIA in retrospective (n=221) and prospective (n=305) derivation cohorts. We calculated likelihood ratios (LR) of result intervals and cut-off values with 100% negative (NPV) and positive (PPV) predictive value for a positive gold-standard functional assay (HIPA). We established a diagnostic algorithm based on the Bayesian combination of pre-test probability and LR of first- and second-line immunoassays. Cut-offs with 100% PPV for positive HIPA were >3.0 U/ml (HemosIL-AcuStar-HIT-IgG) and titre {greater than or equal to}16 (ID-H/PF4-PaGIA); cut-offs with 100% NPV were <0.13 U/ml and {less than or equal to}1, respectively. During the prospective validation of the derived algorithm (n=687), HemosIL-AcuStar-HIT-IgG was used as unique testing in 566/687 cases (82.4%) (analytical TAT 30 min). In 121/687 unresolved cases (17.6%), ID-H/PF4-PaGIA was used as second-line testing (additional TAT 30 min). The algorithm accurately predicted HIT in 51/687 (7.4%) and excluded it in 604/687 (87.9%) patients, leaving only 20/687 (2.9%) cases unresolved. Additionally, we identified 12/687 (1.7%) positive predictions not confirmed by HIPA: 10 patients with probable HIT despite negative HIPA and two possible false positive algorithm predictions. The combination of pre-test probability with first- and second-line immunoassays for anti-PF4/heparin-antibodies is accurate for ruling in or out HIT in {greater than or equal to}95% of cases within 60 minutes. This diagnostic approach improves initial management of patients with suspected HIT.

Inhibition of coagulation factor XII (FXII) activity represents an attractive approach for the treatment and prevention of thrombotic diseases. The few existing FXII inhibitors suffer from low selectivity. Using phage display combined to rational design, we developed a potent inhibitor of FXII with more than 100-fold selectivity over related proteases. The highly selective peptide macrocycle is a promising candidate for the control of FXII activity in antithrombotic therapy and a valuable tool in hematology research.

Background and Purpose-To evaluate whether cisplatin-induced stroke is mediated by vascular toxicity with release of prothrombotic endothelial and platelet-derived microparticles (MPs). Methods-Endothelialand prothrombotic (Annexin V ϩ ) circulating MPs were quantified by flow cytometry in 18 patients with cancer, before and 3 days after administration of cisplatin, and compared with 18 healthy controls. Thrombin-antithrombin complex and prothrombin fragments (F 1ϩ2 ) were measured as markers of the activation of the coagulation. Results-In patients with cancer, baseline levels of circulating prothrombotic, endothelial and platelet-derived MPs were similar to healthy controls and decreased significantly after administration of cisplatin. High-baseline MPs levels were observed in 5 patients who received cisplatin for a second or third cycle. A high-baseline activation of the coagulation was observed in all patients without further increase after cisplatin infusion. Conclusion-Cisplatin treatment is immediately followed by a decrease in circulating levels of endothelial and platelet-derived MPs. However, a transient increase in MPs is observed at the second and third infusion, and this may contribute to the cisplatin-induced stroke.

In the field of thrombosis and haemostasis, many preanalytical variables influence the results of coagulation assays and measures to limit potential results variations should be taken. To our knowledge, no paper describing the development and maintenance of a haemostasis biobank has been previously published. Our description of the biobank of the Swiss cohort of elderly patients with venous thromboembolism (SWITCO65+) is intended to facilitate the set-up of other biobanks in the field of thrombosis and haemostasis. SWITCO65+ is a multicentre cohort that prospectively enrolled consecutive patients aged ≥65 years with venous thromboembolism at nine Swiss hospitals from 09/2009 to 03/2012. Patients will be followed up until December 2013. The cohort includes a biobank with biological material from each participant taken at baseline and after 12 months of follow-up. Whole blood from all participants is assayed with a standard haematology panel, for which fresh samples are required. Two buffy coat vials, one PAXgene Blood RNA System tube and one EDTA-whole blood sample are also collected at baseline for RNA/DNA extraction. Blood samples are processed and vialed within 1 h of collection and transported in batches to a central laboratory where they are stored in ultra-low temperature archives. All analyses of the same type are performed in the same laboratory in batches. Using multiple core laboratories increased the speed of sample analyses and reduced storage time. After recruiting, processing and analyzing the blood of more than 1,000 patients, we determined that the adopted methods and technologies were fit-for-purpose and robust.