Description
Factor VIII ELISA Kit
The VisuLize Factor VIII ELISA Kit is intended to quantitatively measure factor VIII (F8) in human plasma and factor concentrates. The biological importance of factor VIII (F8) is demonstrated in Hemophilia A and those patients suspected of thrombophilia. The laboratory diagnosis of factor VIII (F8) deficiency in Hemophilia A typically involves quantitative determination of factor VIII’s functional activity. The use of this kit in conjunction with functional assays in the area of gene therapy, assessment of factor VIII (F8) concentrates, as well as distinguishing those patients with cross-reactive material will prove useful in the area of Hemophilia A. Additionally as documented in numerous studies, elevated levels of factor VIII (F8) is being recognized as a common risk of venous thrombosis¹, an area where Affinity’s Factor VIII ELISA Kit has utility.
This product is cleared for in vitro Diagnostic use by FDA, Health Canada and CE marked. Available for sale in the United States, Canada and select European countries.
Product Code: FVIII-AG
Features:
- Rapid sandwich ELISA to measure FVIII (F8) antigen (FVIII:Ag)
- 1 hour 55 minutes total incubation time!
- FVIII:Ag reported as International Units/ml traceable to WHO standard for FVIII antigen
- Detection limit to 0.008 IU/ml FVIII:Ag (0.8%)
- Includes normal and low controls
- Shelf-life: 18 months
Applications:
- Quantification of FVIII (F8) in plasma and therapeutic concentrates
- Diagnosis and characterization of Hemophilia A
- Carrier testing for Hemophilia A
- Thrombophilia screening
Species Cross Reactivity: View Chart
Product Datasheet: Factor VIII Complete Antigen ELISA kit - IVD
References: 1.O’Donnell J, Tuddenham EG, Manning R, Kemball-Cook G, Johnson D, Laffan M. High prevalence of elevated factor VIII levels in patients referred for thrombophilia screening: role of increased synthesis and relationship to the acute phase reaction. Thromb Haemost. 1997;77:825–828.
Description of Factor VIII (FVIII)
Factor VIII (formerly referred to as antihemophilic globulin and Factor VIII:C) is a large glycoprotein (320 kDa) that circulates in plasma at approximately 200 ng/ml. Synthesized in the liver, the majority of Factor VIII is cleaved during expression, resulting in a heterogeneous mixture of partially cleaved forms of FVIII ranging in size from 200-280 kDa. The FVIII is stabilized by association with von Willebrand Factor to form a FVIII-vWF complex required for the normal survival of FVIII in vivo (t1/2 of 8-12 hours).
F.VIII is a pro-cofactor that is activated through limited proteolysis by thrombin. In this process F.VIIIa dissociates from vWF to combine with activated Factor IX, calcium and a phospholipid surface where it is an essential cofactor in the assembly of the Factor X activator complex. Once dissociated from vWF, FVIIIa is susceptible to inactivation by activated Protein C and by non-enzymatic decay.
Hemophilia A is a congenital bleeding disorder resulting from an X-chromosome-linked deficiency of FVIII. The severity of the deficiency generally correlates with the severity of the disease. Some Hemophiliacs (~10%) produce a FVIII protein that is partially or totally inactive. The production of neutralizing antibodies to FVIII also occurs in 5-20% of Hemophiliacs 1-3.
References and Review
- Lollar P, Fay PJ, Fass DN; Factor VIII and Factor VIIIa. Methods in Enzymology, 222, pg 122, 1993.
- Hoyer, LW, Wyshock EG, Colman RW, in Hemostasis and Thrombosis, 3rd Edition, eds. RW Colman, J Hirsh, VJ Marder and EW Salzman, pp. 109-133, J.B. Lippincott Co., Philadelphia, 1994.
- Pittman DD, Kaufman RJ. Structure-Function Relationships of Factor VIII Elucidated through Recombinant DNA Technology. Thromb. Haemostas. 61:161-165, 1989.
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抗人球蛋白试验，又称Coombs’试验，是诊断自身免疫性溶血性贫血(AIHA)的重要依据。
正常人直接与间接试验均为阴性，Coombs’试验阴性有时并不能排除AIHA
本试验阳性结果主要见于下列几种情况：
1.自身免疫性贫血，（IgG）型引起的溶血性贫血，本试验直接反应常呈强阳性，间接反应大多阴性，但亦可阳性。
2.药物诱发的免疫性溶血性贫血①α-甲基多巴型：直接及间接反应均阳性。②青霉素型：直接反应阳性，间接反应阴性，以上二型如以正常红细胞先与有关药物于37℃培育后再加病人血清、间接反应均为阳性。③福阿亭型：（奎宁等药物）抗体通常为IgM，偶有IgG型者，直接反应为阳性，间接反应阴性，但如用IgG抗血清做试剂则结果大部分均为阴性，但如培育时加入新鲜正常人血清（供应补体）则结果为阳性。
3.冷凝集素综合征直接反应阳性，间接反应阴性（试验需在37℃下进行）由于本病红细胞膜附着的是补体C4和C3而不是IgG或IgM，如果用抗IgG或抗IgM抗血清做试验时，则结果阴性，如以抗补体的抗血清做试验则直接反应阳性。
4.新生儿同种免疫溶血病，因Rh血型不合所致溶血病，直接及间接反应均强阳性，持续数周、换血输血后数天内可变为阴性，由于“ABO”血型不合引起的溶血病，结果常为阴性或弱阳性。
5.红细胞血型不合引起的输血反应，ABO或Rh血型不合输血，供者的红细胞被受者的血型抗体致敏，在供者被致敏的红细胞完全破坏以前，直接反应阳性，Rh阴性者如过去不曾接受过Rh阳性者的血或曾妊娠胎儿为Rh阳性者，间接反应阳性，如无上述接触，第一次输血后（Rh阳性的血），数天之内间接反应也会变为阳性。
6.其它在传染性单核细胞增多症、SLE、恶性淋巴瘤、慢性淋巴细胞白血病、癌肿、铅中毒、结节性动脉周围炎、EVan氏综合征等，病人直接反应亦可阳性，阵发性寒冷性血红蛋白尿症患者中，急性发作后用抗补体血清做试验直接反应常为阳性。展开
