Measurement of alloantibodies against FⅧ in patients with hemophilia A using a newly-developed ELISA and its clinical application / 中华检验医学杂志

ABSTRACT

Objective An ELISA-based assay for detecting alloantibodies against FⅧ was established to estimate the incidence of alloantibodies against FⅧ in treated patients with hemophilia A. Methods One hundred and forty patients with hemophilia A and 80 healthy controls were enrolled. Among hemophilia A patients, 84, 34 and 22 patients were in severe, moderate and mild conditions respectively. All patients were treated with plasma-derived FⅧ concentrates before. The titer wells were coated with MoAb against FⅧ which was developed in our laboratory. Then human recombinant FⅧ concentrates were applied. After incubation in room temperature for 2 hours, diluted plasma samples and HRP-conjugated goat anti-human IgG were added successively. Finally Absorbance (A490) were measured and recorded. Inhibitor activity against FⅧ for all plasma samples was measured by a modified Nijmegen assay simultaneously. Results The results showed that alloantibodies against FⅧ were found in 40.0% (56/140) patients by ELISA. And the alloantibody incidences in the severe and non-severe patients were 47.6% (40/84) and 28.5% (16/56)respectively. There was statistical significance between these two categories (x2 = 5.079, P ＜ 0.05 ). The FⅧ inhibitor activity was detected in 24.3% (34/140) patients by modified Nijmegen assay. The inhibitor incidences in the severe and non-severe patients were 33.3% (28/84) and 10.7% (6/56) respectively.There was statistical significance (x2 = 9.349, P ＜ 0.05). Twenty-five patients were positive for FⅧ alloantibodies by ELISA but had no FⅧ inhibitor activity by the modified Nijmegen assay. The positive rates of FⅧ alloantibodies and inhibitor activity were 40.0% (56/140) and 24.3% (34/140) respectively,which had significant difference (x2 = 15.75, P ＜ 0.01 ) and strong positive correlation ( rn = 0.59, P ＜0.01 ). Meanwhile the results deduced from these two tests shared a high consistency rate ( Kappa = 0.55,P ＜0.01 ). Conclusions The detection rate for alloantibodies against F Ⅷ is enhanced by our newlydeveloped ELISA. Our results suggest that the occurrence of the alloantibodies against F Ⅷ in Chinese hemophilia A patients is not rare and the alloantibody incidence is preponderant in the patients with severe hemophilia A compared with non-severe hemophilia A patients.