DETECTION AND QUANTITATION OF CLEAVED AND UNCLEAVED HIGH MOLECULAR WEIGHT KININOGEN IN PLASMA BY LIGAND BLOTTING WITH RADIOLABELED PLASMA PREKALLIKREIN OR FACTOR XI
A method for the quantitative assay of native single chain and kallikrein cleaved two-chain high molecular weight kininogen (HMWK) in plasma has been developed. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of whole plasma is followed by electroblotting of the electropherogram to nitrocellulose membranes and detection of the inmobilized HMWK with its physiologic ligands, plasma prekallikrein or factor XI. Using 1251-prekallikrein or 125I-F.XI overlay nitrocellulose bound HMWK can be visualized by autoradiography.Using unreduced SDS-PAGE cleaved two-chain HMWK (Mr 107,000 and 95,000) is electrophoretically separated from uncleaved single chain HMWK (Mr 150,000). Counting the radioactivity of the nitrocellulose pieces corresponding to cleaved HMWK permits its quantitative measurement by comparison with standards consisting of decreasing amounts of fully dextran sulfate activated normal human plasma. Single chain HMWK is similarly assayed using reduced SDS-PAGE and unactivated normal human plasma standards.This technique is highly specific and sensitive to ˜ 50 ng of either cleaved or uncleaved HMWK. Varying concentrations of cleaved HMWK were found in plasmas from patients suffering from various systemic inflanmatory conditions. Higher levels of in vivo cleaved HMWK were observed during acute attacks of hereditary angioedema due to Cl-inhibitor deficiency.This technique may be useful for the assessment of the degree of in vitro or in vivo activation of the contact system of plasma.