Heparin cofactor II assay. Elimination of heparin and antithrombin-III effects.
Functional assays for heparin cofactor II (HC-II) are based on the inactivation of thrombin by HC-II in the presence of dermatan sulfate (DS). Residual thrombin is measured in a chromogenic assay. Interference by the antithrombin-III (AT-III)/heparin complex, which also rapidly inactivates thrombin, must be eliminated from the HC-II test system. Commercial DS is contaminated with heparin, while plasma specimens to be tested contain AT-III. After NaNO2/acetic acid treatment of DS (to inactivate heparin), there was enough residual heparin to cause AT-III interference. Treatment of plasma with commercially available anti-AT-III antiserum largely, but not completely, removed AT-III interference from the HC-II assay. With commercially available reagents, both NaNO2/acetic acid treatment of DS and anti-AT-III treatment of plasma were needed to eliminate heparin/AT-III interference. Protamine sulfate inactivated DS as well as heparin and could not be used to reduce AT-III/heparin interference with the HC-II assay.
Nakhleh
R
R
Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota, Minneapolis.
Vogt
J M
JM
Edson
J R
JR
D000085:Acetates / Q000494:pharmacology; D019342:Acetic Acid; D000990:Antithrombin III / Q000037:antagonists & inhibitors* / Q000276:immunology; D006023:Glycoproteins / Q000032:analysis*; D006494:Heparin Antagonists / Q000494:pharmacology*; D015844:Heparin Cofactor II; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D008722:Methods; D009994:Osmolar Concentration; D012977:Sodium Nitrite / Q000494:pharmacology
D000085:Acetates; D006023:Glycoproteins; D006494:Heparin Antagonists; D007106:Immune Sera; D015844:Heparin Cofactor II; D000990:Antithrombin III; D012977:Sodium Nitrite; D019342:Acetic Acid