Bajaj S P, Rapaport S I, Barclay S, Herbst K D
Blood. 1985 Jun;65(6):1538-43.
A patient developed bleeding due to an acute acquired specific prothrombin deficiency. Unlike previously described patients, this patient had no evidence of an associated lupus anticoagulant. Prothrombin activity and antigen were decreased concordantly and the patient's plasma did not neutralize the activity of added prothrombin or interfere with its measurement by electroimmunoassay. Nevertheless, immunoelectrophoresis and experiments using 125I-prothrombin revealed a prothrombin-binding antibody. The residual prothrombin in the patient's plasma was in the form of a prothrombin-antibody complex. Administration of adrenal corticosteroids was associated with a rise in prothrombin activity and cessation of bleeding, but circulating prothrombin was still bound to the antibody. This suggests that non-neutralizing antibodies to prothrombin cause plasma prothrombin deficiency because of a rapid clearance of prothrombin-antibody complexes, which is slowed by adrenal corticosteroids. The antibody had a relatively low affinity for prothrombin (Kd 5 to 8 X 10(-7)) and was transient. It is possible, therefore, that the antibody arose not to prothrombin itself, but to an antigen sharing an epitope with prothrombin.
一名患者因急性获得性特异性凝血酶原缺乏而出现出血。与先前描述的患者不同，该患者没有相关狼疮抗凝物的证据。凝血酶原活性和抗原同时降低，且患者血浆不能中和添加的凝血酶原活性，也不干扰其免疫电泳测定。然而，免疫电泳和使用125I-凝血酶原的实验显示存在一种凝血酶原结合抗体。患者血浆中的残余凝血酶原呈凝血酶原-抗体复合物形式。给予肾上腺皮质激素后凝血酶原活性升高且出血停止，但循环中的凝血酶原仍与抗体结合。这表明针对凝血酶原的非中和性抗体由于凝血酶原-抗体复合物的快速清除而导致血浆凝血酶原缺乏，而肾上腺皮质激素可减缓这种清除。该抗体对凝血酶原的亲和力相对较低（解离常数Kd为5至8×10(-7)）且是短暂的。因此，有可能该抗体并非针对凝血酶原本身，而是针对与凝血酶原共享一个表位的抗原产生的。
