title: Assessment of Hageman factor activation in human plasma: quantification of activated Hageman factor-C1 inactivator complexes by an enzyme-linked differential antibody immunosorbent assay.
abstract: An enzyme-linked immunosorbent assay has been developed for the quantitation of activated Hageman factor-C1 inactivator (HF-C1 INH) complexes. Addition of increasing quantities of either of the major forms of activated Hageman factor (HFa or HFf) to normal plasma or to Hageman factor-deficient plasma leads to a dose-dependent increase in activated HF-C1 INH complexes. As little as 0.5 micrograms/mL of activated HF added to plasma can be detected, corresponding to activation of approximately 2% of plasma HF. The sensitivity of the assay is increased at least tenfold when complexes are formed in HF-deficient plasma, indicating competition between unactivated HF and activated HF-C1 INH complexes for binding to the antibody. Specificity is demonstrated in that addition of activated HF to hereditary angioedema plasma yields less than 1% of the activated HF-C1 INH complex formation obtained with normal plasma. Kaolin activation of HF-deficient plasma yields no detectable complex formation. Kaolin activation of prekallikrein-deficient plasma demonstrates a time-dependent increase in formation of activated HF-C1 INH complex consistent with the ability of HF in this plasma to autoactivate as the time of incubation with the surface is increased. Kaolin treatment of high-molecular weight (HMW) kininogen-deficient plasma yields an even more profound abnormality in the rate of formation of activated HF-C1 INH complexes reflecting the complex role of HMW kininogen in the initiation of contact activation. Although addition of corn inhibitor to plasma prevents activated HF-C1 INH complex formation, it does not inhibit activated HF sufficiently fast to prevent prekallikrein activation.
mesh_terms: D001777:Blood Coagulation; D003174:Complement C1 Inactivator Proteins / Q000276:immunology / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D005174:Factor XII / Q000032:analysis* / Q000502:physiology; D015956:Factor XIIa; D006801:Humans; D007518:Isoantibodies; D007610:Kallikreins / Q000032:analysis; D007616:Kaolin; D010314:Partial Thromboplastin Time; D010446:Peptide Fragments / Q000032:analysis* / Q000502:physiology
chemical_list: D003174:Complement C1 Inactivator Proteins; D007518:Isoantibodies; D010446:Peptide Fragments; D007616:Kaolin; D005174:Factor XII; D007610:Kallikreins; D015956:Factor XIIa