Assessment of Hageman factor activation in human plasma: quantification of
activated Hageman factor-C1 inactivator complexes by an enzyme- linked
differential antibody immunosorbent assay
AP Kaplan, B Gruber and PC Harpel
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.
Volume 66,
Issue 3,
pp. 636-641,
09/01/1985
Copyright © 1985 by The American Society of Hematology
