O. Takamiya et S. Kinoshita, A SIMPLE METHOD FOR DETECTION OF HUMAN FACTOR-IX INHIBITOR USING ELISA, Scandinavian journal of clinical & laboratory investigation, 57(8), 1997, pp. 683-688
We developed a simple ELISA for FIX inhibitors (FIXinh). The relations
hip between absorbance and various dilutions of plasma containing know
n FIXinh (28 Bethesda units/ml) was linear, ranging from 200 to 25 600
-fold dilution on semi-log paper. Converted into the value of Bethesda
Inhibitor Assay, ELISA can detect as low as 0.219 Bethesda units/ml.
Absorbance for 30 normal individuals was 0.213+/-0.008, which correspo
nds to <0.44 Bethesda units/ml. With ELISA, only the value for hemophi
lia B with FIXinh, which was revealed as positive by Bethesda Inhibito
r Assay, was significantly higher than that of normal controls, hemoph
ilia B without FIXinh, hemophilia A with FVIIIinh and systematic lupus
erythematosus (SLE) with lupus anticoagulant (LA). The value in the p
atient with SLE, who had a high level of FVIIIinh (1000 Bethesda units
/ml), was 3 Bethesda units/ml of FIXinh with Bethesda Inhibitor Assay,
which was not significantly higher than that of normal subjects with
ELISA. FIXinh in hemophilia B patients by ELISA for FIXinh was not aff
ected by the presence of other anticoagulants.