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This study reports the K070 monoclonal antibody, a human-mouse recombinant chimeric monoclonal antibody, IgG1 isotype, targeted to Heparin and PF4 complexes, which mimics Heparin Induced Thrombocytopenia. This antibody has a strong reactivity to Heparin-PF4 complexes, and a much weaker one to PF4 alone. When plasmas spiked with this antibody at concentrations ≥ 0.5 µg/ml are tested at the standard immunoassay dilution, a dose dependent reactivity is obtained. This opens the perspective to use this material to calibrate immunoassays for a quantitative measurement of heparin dependent antibodies, when the disease is suspected. Furthermore, when plasmas are spiked at a higher concentration, from 20 to 200 µg/ml, they test positive in functional assays, like Platelet Aggregation/Activation Tests or Flow Cytometry methods, in presence of a low (0.1-1.0 IU/ml) but not a high (10-100 IU/ml) heparin concentration. In functional assays K070 reactivity level depends on the platelet rich plasmas used. In Platelet Aggregometry Tests some platelet rich plasmas are already positive when tested with plasmas supplemented with 20 µg/ml, whilst others require 100 to 200 µg/ml. At this latter concentration, all tested plasmas generate a strong positive responses with functional assays. K070 is then a useful antibody for calibration of immunoassays and standardization of functional methods used to diagnose Heparin Induced Thrombocytopenia.