Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University, Giessen, Germany.
Transfusion. 2021 Jun;61(6):1916-1922. doi: 10.1111/trf.16359. Epub 2021 Mar 18.
CD177 is a surface protein on neutrophils and a main mediator for the surface expression of proteinase 3 (PR3). Its functions are largely unknown. At least three types of antibodies have been described to target CD177: isoantibodies, which are formed in CD177-null individuals as a result of an immune reaction following transfusion or pregnancy; autoantibodies present in sera from patients with autoimmune neutropenia; and antineutrophil cytoplasmic antibodies in sera from patients with glomerulonephritis with polyangiitis. In this study, we aimed to compare the binding characteristics of auto- and iso-antibodies to optimize their detectability in the neutrophil serology laboratory.
The reactivity of iso- and auto-antibodies against CD177 was studied using granulocytes, "native" CD177/PR3 complex, and recombinant CD177 or PR3.
All iso- and auto-antibodies were reactive with CD177/PR3 when immobilized with monoclonal antibody (moab) 7D8. Seventy-five percent of autoantibodies, but none of the isoantibodies, did not react with CD177/PR3 immobilized with moab MEM166. The majority of autoantibodies did not react with recombinant CD177, whereas most isoantibodies tested positive.
Our results suggest that iso- and auto-antibodies against CD177 target different epitopes. Isoantibodies mainly target CD177 alone, while the majority of autoantibodies target a native epitope present on the neutrophil surface, but absent from recombinant CD177 which lacks PR3. Moab MEM166 binds to the native epitope and hinders the binding of CD177 autoantibodies. The results may help to design diagnostic strategies, especially for the identification of autoantibodies.
CD177 是中性粒细胞表面的一种蛋白，也是蛋白酶 3（PR3）表面表达的主要介质。其功能在很大程度上尚不清楚。已经描述了至少三种针对 CD177 的抗体类型：同种异体抗体，这些抗体是在 CD177 缺失个体中形成的，是由于输血或妊娠后的免疫反应；自身抗体存在于自身免疫性中性粒细胞减少症患者的血清中；以及抗中性粒细胞胞质抗体存在于伴有多血管炎的肾小球肾炎患者的血清中。在这项研究中，我们旨在比较自身抗体和同种异体抗体的结合特性，以优化其在中性粒细胞血清学实验室中的可检测性。
使用粒细胞、“天然”CD177/PR3 复合物、重组 CD177 或 PR3 研究同种异体和自身抗体对 CD177 的反应性。
所有同种异体和自身抗体与用单克隆抗体（moab）7D8 固定的 CD177/PR3 均有反应。75%的自身抗体，但没有任何同种异体抗体，与用 moab MEM166 固定的 CD177/PR3 没有反应。大多数自身抗体与重组 CD177 没有反应，而大多数测试的同种异体抗体呈阳性。
我们的结果表明，针对 CD177 的同种异体和自身抗体针对不同的表位。同种异体抗体主要针对单独的 CD177，而大多数自身抗体针对存在于中性粒细胞表面的天然表位，但不存在于缺乏 PR3 的重组 CD177 中。moab MEM166 结合到天然表位上，阻碍了 CD177 自身抗体的结合。这些结果可能有助于设计诊断策略，特别是用于鉴定自身抗体。
