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Studies on immunological assay of vitamin K dependent factors
Author(s) -
Mikami S.,
Tuddenham E. G. D.
Publication year - 1986
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1986.tb02915.x
Subject(s) - immunoradiometric assay , radioimmunoassay , chemistry , chromatography , pharmacology , medicine , biochemistry
S ummary . We describe and compare five assay systems for Protein C (PC) in human plasma; a functional assay for PC activity, Laurell electroimmunoassay with EDTA or calcium (EDTA‐Laurell or Ca‐Laurell), radioimmunoassay (RIA) and immunoradiometric assay (IRMA). The lower limit of sensitivity of PC in normal reference plasma was 2 × 10 −3 units/ml by RIA and 1 × 10 −4 units/ml by IRMA, but the ratio of maximum binding to blank binding was superior in RIA. In normal plasma (= 20), there was no significant discrepancy of PC levels between RIA, Laurell (EDTA − and Ca − ) and functional assay. In normal serum, PC antigen (PC:AG) measured by Ca‐Laurell showed a high value (1.37 0.24 units/ml) compared to the other assays. PC:AG of a purified sample increased its level by Ca‐Laurell method during activation by thrombin. Activated PC (PCa) has decreased affinity for anti‐PC rabbit IgG, similarly to decarboxy (warfarinized) PC. In warfarin‐treated individuals (= 12) who were anticoagulated orally for more than 3 weeks, functional activity was lower (0.27 0.12 units/ml) than that measured by RIA (0.64 0.12 units/ml) or EDTA‐Laurell (0.62 0.06 units/ml), whereas PC:AG measured by CA‐Laurell had a normal value of 0.96 0.40 units/ml. After stopping administration, the activity showed a gradual increase to the normal at 2 weeks, while PC:AG increased more rapidly to normalize in 1 week.