Heparin-Sepharose affinity chromatography of plasma from a carrier of antithrombin Wibble, with peak III being the normal component (-antithrombin) and peak IV the abnormal antithrombin Wibble. Latent antithrombin was shown in a control procedure to give a shoulder on the first peak indicated by dashed line. The corresponding peak II from the plasma sample was almost completely latent-antithrombin Wibble (see Fig 3D).