Immunoblots of 6-hour samples from all 12 volunteers.

Monoclonal antibody MAb 2B5 against the neo–N-terminus of the fibrin α-chain was used for detection in panel A, MAb S4H9 against D-dimer antigen in panel B, and polyclonal antifibrinogen antiserum in panel C. For reference, pooled plasma samples from patients with fibrinolytic therapy (FL) and patients with disseminated intravascular coagulation (DIC) are included. MAb 2B5-reactive material consists primarily of fibrin monomer, fragment X, and fragment Y (panel A). MAb S4H9 detects several high-molecular-weight bands and fragment D-dimer of cross-inked fibrin, but also reacts with fragments X, Y, and D of non–cross-linked fibrin or fibrinogen (panel B). Immunostaining with the polyclonal antifibrinogen antiserum shows that fragments X, Y, and D are the prevailing proteolytic derivatives, whereas the D-dimer band is less prominent (panel C).