Esnouf M P, Burgess A I, Dodds A W, Sarphie A F, Miller G J
Nuffield Department of Clinical Biochemistry, University of Oxford, The Radcliffe Infirmary, UK.
Thromb Haemost. 2000 Jun;83(6):874-81.
A monoclonal antibody (mAb 2/215) against human beta-factor XIIa (beta-FXIIa), was shown by equilibrium binding studies to have a high affinity for alpha-factor XIIa (alpha-FXIIa) (Kd 1.8 nM) and beta-FXIIa (Kd 0.65 nM) but no detectable reaction with FXII zymogen or alpha-FXIIa:C1 esterase inhibitor (C1-INH) complex. Surface plasmon resonance studies showed that the mAb 2/215 bound to immobilized alpha-FXIIa with high affinity (KD 3.93 +/- 1.46 x 10(-11) M). Western blots employing mAb 2/215 indicated that human plasma contained small amounts of alpha-FXIIa but no beta-FXIIa. mAb 2/215 did not inhibit the amidolytic activity of beta-FXIIa and protected beta-FXIIa from inhibition by C1-INH. The recovery by ELISA,employing mAb 2/215 as the capture antibody, of alpha-FXIIa added to plasma was 11.3%, 42% after inhibition of alpha-FXIIa with 3:4dichloroisocoumarin, and 82% when 0.5% Triton-X100 was added to the assay. Gel filtration showed that the majority of plasma alpha-FXIIa existed as a complex (Mr approximately 170,000). This distinctive mAb increases the capacity to study the contact system in health and disease.
一种针对人β-因子XIIa（β-FXIIa）的单克隆抗体（mAb 2/215），通过平衡结合研究表明对α-因子XIIa（α-FXIIa）具有高亲和力（解离常数Kd为1.8 nM），对β-FXIIa也具有高亲和力（Kd为0.65 nM），但与因子XII酶原或α-FXIIa：C1酯酶抑制剂（C1-INH）复合物无明显反应。表面等离子体共振研究表明，mAb 2/215以高亲和力（KD为3.93±1.46×10⁻¹¹ M）结合固定化的α-FXIIa。使用mAb 2/215的蛋白质免疫印迹表明，人血浆中含有少量α-FXIIa，但不含β-FXIIa。mAb 2/215不抑制β-FXIIa的酰胺水解活性，并能保护β-FXIIa不被C1-INH抑制。以mAb 2/215作为捕获抗体，通过酶联免疫吸附测定法（ELISA）测得，添加到血浆中的α-FXIIa的回收率为11.3%，用3,4-二氯异香豆素抑制α-FXIIa后回收率为42%，当在测定中添加0.5% Triton-X100时回收率为82%。凝胶过滤显示，血浆中大部分α-FXIIa以复合物形式存在（相对分子质量约为170,000）。这种独特的单克隆抗体提高了在健康和疾病状态下研究接触系统的能力。
