Acquired Inhibitors of Plasma Factor Ix a Study of Their Induction, Properties and Neutralization

Genetic variants of hemophilia B: detection by means of a specific PTC inhibitor

“…It is interesting to note, however, that in control studies, materials lacking PTC (buffer andl BaSO4-adsorbed normal plasma) are also deficient in inhibitor-neutralizing activity. Further evidence to suggest that the patients with decreased inhibitor-iieutralizing activity may be deficient in PTC-like protein has been previously reported from our laboratory (2). We found that a patient who de-veloped a specific PTC-inhibitor after transfusions of normal plasma that contained PTC did not do so when transfused with plasma obtained from hemophilia B patients whose plasma contained no detectable inhibitor-neutralizing activity.…”

“…Previous observations have shown that plasma from most severely affected hemophilia B patients (loes not contain material capable of neutralizing a specific PTC-inhibitor (2,4). On the other hand, a single patient whose plasma did contain inhibitor-neutralizing activity has been' reported (4).…”

“…R'cei'z'cd for pmiblicatiu, 31 .to/v 17(067 amd in rcviscd fMr1;, 22 September 1967. factor) ( 1,2). Properties of this inhibitor strongly suggested that it was an antibody against PTC (3).…”

Purification and characterization of an abnormal factor IX (Christmas factor) molecule. Factor IX Chapel Hill.

“…Factor XI was assayed with artificially depleted human plasma (30) as well as plasma congenitally deficient in Factor XI (31). Factor IX immunological activity was assayed by an inhibitor-neutralization technique (12,21). Factor IX was also measured by a radioimmunoassay with purified normal human Factor IX and a human anti-Factor IX antibody (32).…”

“…Elucidation of the nature of the defect in abnormal Factor IX molecules found in some patients with hemophilia B (Christmas disease) may provide insights into function of normal Factor IX in hemostasis and its interaction with other clotting factors. Roberts et al (12), and other investigators (13)(14)(15)(16)(17)(18)(19) have demonstrated that some patients with hemophilia B possess an abnormal Factor IX molecule which has low to undetectable clotting activity, but which is present in relatively normal amounts when measured by immunological techniques (12,(20)(21)(22). Because they contain cross-reacting material (CRM)l to specific homologous and heterologous anti-Factor IX antibodies, these patients have been termed CRM+ (CRM positive variants).…”