An Immunological Investigation of Hemophilia B with a Tentative Classification of the Disease into Five Variants

Abstract

23 patients with hemophilia B have been investigated by means of several immunological methods. 16 patients (69.9%) had no detectable factor XI antigen. Five had a normal factor IX antigen and the electrophoretic mobility of this abnormal factor IX was similar to that of its normal counterpart. One of these five patients had hemophilia B(m), since ox brain thromboplastin clotting time was severely prolonged. The remaining two patients had reduced or decreased factor IX antigen. Several patients showed a slight prolongation of ox brain thromboplastin time due to an associated slight factor VII deficiency. On the basis of these results, a tentative classification of hemophilia B into five variants is proposed, namely: hemophilia B-, or with no factor IX antigen; hemophilia B+, or with normal factor IX antigen; hemophilia B(ra), or with reduced factor IX antigen; hemophilia B(m), or with normal factor IX antigen and severely prolonged ox brain thromboplastin; hemophilia B, usually B-, with associated mild factor VII defect. A complete evaluation of the hemophilia B patients is feasible only by means of a battery of tests, namely : factor IX activity assay, factor IX antigen determination, ox brain thromboplastin clotting time, factor VII activity assay.

Sensitive Solid Phase Enzyme Immunoassay for Factor IX Antigen and Classification of Hemophilia B

“…One quarter of the patients were considered to have anomalies of factor IX molecule. These results are identical with those of other authors [5,25,26], Chung et al [28] reported that an abnor mal factor IX molecule (factor IX Chapel Hill) was similar to normal in that the Nterminal tyrosine, molecular weight, amino acid composition and content of y-carboxyglutamic acid residues were the same as nor mal. However, factor IX Chapel Hill exhib ited delayed activation in the presence of fac tor XIa and calcium [28].…”

“…However, its sensitivity was as low as 4 X 10-3U/ml of plasma, and the procedures were cumbersome [25]. The El A described here was highly sensitive without the use of monospecific antiserum, and IX: AG levels as low as 10-4 U/ml could be measured in con trast to the previous assays [25][26][27], From 27 families, we have studied the plasma of 37 patients with hemophilia B. 36 of these pa tients had severe disease (factor IX procoagu lant activity less than 0.01 U/ml).…”

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

“…In Fig. 3 15 ,ig of purified Factor IXCH was electrophoresed on 7.5% polyacrylamide as shown in the top panel. The protein was identified by staining with Coomassie Blue.…”

“…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).…”

Clotting Factors and Platelets

“…This was a neutralizing antiserum, since it failed to give a precipitate in electroimmunoassay [11], Rabbit anti-human factor IX was also supplied by Dr. N. Heimburger, Behringwerke Laboratories. This antiserum yielded clear factor IX rockets or precipitates in electroimmunoassay and in bidimensional immunoelectrophoresis systems [12]. Goat anti-rabbit immunoglobulin antiserum, fluorescein isothiocyanate (FITC)-conjugated and goat anti-rabbit -/-globulin were supplied by Behringwerke Laboratories.…”