F9 Antibody

Coagulation Factor IX, also known as Christmas factor, is a crucial protein in the blood coagulation process. It is a serine protease that belongs to the peptidase family S1 and plays a significant role in the coagulation cascade, which is essential for hemostasis and normal blood clotting . Deficiency of this protein leads to a bleeding disorder known as hemophilia B .

Factor IX was discovered in 1952 after a young boy named Stephen Christmas was found to be lacking this specific factor, leading to hemophilia . This discovery led to the naming of the protein as “Christmas factor.” It is one of the essential medicines listed by the World Health Organization .

Factor IX is produced as a zymogen, an inactive precursor, which is processed to remove the signal peptide, glycosylated, and then cleaved by factor XIa or factor VIIa to produce an active two-chain form linked by a disulfide bridge . When activated into factor IXa, in the presence of calcium ions, membrane phospholipids, and a Factor VIII cofactor, it hydrolyzes one arginine-isoleucine bond in factor X to form factor Xa . Factor IX is inhibited by antithrombin .

The protein is composed of four domains: the Gla domain, two tandem copies of the EGF domain, and a C-terminal trypsin-like peptidase domain, which carries out the catalytic cleavage . The N-terminal EGF domain is responsible for binding tissue factor, while the second EGF domain mediates binding to platelets and assembly of the factor X activating complex .

Mouse antibodies are immunoglobulins produced by mice in response to antigens. These antibodies can be used in various research and therapeutic applications. However, when mouse antibodies are introduced into humans, they can trigger an immune response known as the Human Anti-Mouse Antibody (HAMA) response . This response can range from mild reactions, such as rashes, to severe reactions, such as kidney failure . The HAMA response can also decrease the effectiveness of the treatment and complicate laboratory measurements .

Mouse antibodies against coagulation factor IX are used in research to study the protein’s structure, function, and role in the coagulation cascade. These antibodies can also be used in diagnostic assays to detect factor IX levels in blood samples. In therapeutic applications, recombinant factor IX is used to treat hemophilia B patients by replacing the deficient protein .