Identification of a defective factor XI cross-reacting material in a factor
XI-deficient patient
C Mannhalter, P Hellstern and E Deutsch
A homozygous factor XI-deficient girl, who appeared to be positive for
cross-reacting material (CRM+) was studied for clarification. Factor XI
antigen (F XI:Ag) was measured by radial immunodiffusion using
monospecific, heterologous anti-factor XI antibodies. Factor XI coagulant
activity (F XI:C) was determined in a modified activated partial
thromboplastin time (APTT) test. The ratio of F XI:C to F XI:Ag was 0.04
for the proposita, as compared with 0.7 to 0.74 in the other family
members. In contrast, 12 normal individuals had ratios of F XI:C to F XI:Ag
of 1.04 +/- 0.15. F XI esterolytic activity was clearly higher than F XI:C
in the proband, but not in her relatives. Immunoblotting studies
demonstrated F XI CRM in the patient's plasma. Chromatography on
diethylaminoethanol (DEAE)-Sephadex at pH 8.4 led to an almost complete
removal of F XI from the plasma. The defective F XI was not bound to a
negatively charged kaolin surface due to an abnormal interaction with
high-mol-wt kininogen (HMWK).
Volume 70,
Issue 1,
pp. 31-37,
07/01/1987
Copyright © 1987 by The American Society of Hematology
