von Willebrand因子(vWF)のヒトType Ⅲ collagenへの結合に関する研究 ： Ⅱ. von Willebrand病および血友病A患者血漿中のvWFのcollagen結合

Abstract

The percentage of binding of vWF to human Type Ⅲ fibrillar collagen was determined in plasma samples from 20 patients with various types of von Willebrand disease (vWD) and 27 patients with hemophilia A. The levels of collagen binding were normal, ranging from 83.6 to 90.0% in 9 cases of Type 1 vWD. In 7 cases of Type ⅡA vWD and 3 cases of Type ⅡB vWD, the rates of collagen binding were 42.0～76.1% and 68.0～80.0% respectively. A case of Type ⅡC vWD showed a remarkable decrease, with 35.8%. On the other hand, 27 cases of hemophilia A showed normal values with 91.0～98.7%. When plasma samles absorbed with collagen and then vWF multimer in the supernatant were analysed by agarose-gel electrophoresis, the larger multimer of normal vWF showed the strongest affinity to collagen, while the smallest one was poor. Changes of vWF multimer in Type Ⅰ vWD showed the same results as those of normal plasma, but Types ⅡA, ⅡB and ⅡC vWD showed a decreased affinity of intermediate and smaller multimer to collagen. These findings suggest that the poor affinity of vWF of Types ⅡA, ⅡB and ⅡC vWD to collagen may be caused by abnormality of the collagen binding domain in vWF subunit.