title: Identification of a defective factor XI cross-reacting material in a factor XI-deficient patient.
abstract: 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).
mesh_terms: D000941:Antigens / Q000032:analysis* / Q000276:immunology; D002850:Chromatography, Gel; D004796:Clinical Enzyme Tests; D003101:Collodion; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D004610:Ellagic Acid / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D000939:Epitopes; D005172:Factor XI / Q000032:analysis / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D005173:Factor XI Deficiency / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D005174:Factor XII / Q000276:immunology; D015945:Factor XIa; D005260:Female; D006801:Humans; D005779:Immunodiffusion; D007616:Kaolin / Q000494:pharmacology; D010314:Partial Thromboplastin Time; D010375:Pedigree
chemical_list: D000941:Antigens; D000939:Epitopes; D004610:Ellagic Acid; D007616:Kaolin; D005174:Factor XII; D003101:Collodion; D005172:Factor XI; D015945:Factor XIa