Davies A, Wilson A B, Bramley J C, Willers C, Van Heyningen V, Bickmore W A, Lachmann P J
Molecular Immunopathology Unit, Medical Research Council Centre, Cambridge, UK.
Immunology. 1995 Jun;85(2):220-7.
The MIC 11 antigen is expressed on human cells and is characterized by reaction with a monoclonal antibody (mAb), 16.3A5. The gene controlling MIC 11 was recently mapped to the p13 region of chromosome 11 within 500 kb of the gene encoding CD59, a complement regulatory protein. The present report investigates the antigenic relationship between these cell-membrane determinants and sets out evidence that MIC 11 and CD59 are encoded by the same gene. Western blotting of human erythrocyte membrane proteins and purified membrane CD59 showed that 16.3A5 anti-MIC 11 antibody bound to a 19-24,000 MW band with the characteristic appearance of CD59 protein, and gave staining patterns identical to those obtained with the CD59 antibody, BRIC 229. The binding of 16.3A5 monoclonal IgG to purified urine-derived CD59 in enzyme-linked immunosorbent assay (ELISA) was inhibited by YTH 53.1 rat CD59 antibody, indicating that the MIC 11 epitope is the same as, or close to, that recognized by CD59 antibodies such as YTH 53.1, BRIC 229 and 2/24. Prior exposure of erythrocytes to 16.3A5 anti-MIC 11 also reduced the ability of the CD59 antibodies, BRIC 229 and YTH 53.1, to block the complement-inhibiting function of membrane CD59. Anti-MIC 11 antibody alone, however, had no inhibitory effect on CD59 function. This may be due to its relatively low binding affinity or to some slight difference in epitope specificity. Further studies using immunofluorescence showed that the MIC 11 epitope, like CD59, is absent from EBV-B cells lacking GPI-anchored proteins and from a B-cell line specifically deficient in CD59 protein. Overall, the results provide strong evidence that MIC 11 is a determinant on the CD59 molecule.
MIC 11抗原在人细胞上表达，其特征是能与单克隆抗体（mAb）16.3A5发生反应。控制MIC 11的基因最近被定位到11号染色体的p13区域，位于编码补体调节蛋白CD59的基因的500 kb范围内。本报告研究了这些细胞膜决定簇之间的抗原关系，并提出证据表明MIC 11和CD59由同一基因编码。对人红细胞膜蛋白和纯化的膜CD59进行蛋白质印迹分析表明，16.3A5抗MIC 11抗体与一条19 - 24,000 MW的条带结合，该条带具有CD59蛋白的特征性外观，且染色模式与用CD59抗体BRIC 229获得的模式相同。在酶联免疫吸附测定（ELISA）中，YTH 53.1大鼠CD59抗体可抑制16.3A5单克隆IgG与纯化的尿源性CD59的结合，这表明MIC 11表位与YTH 53.1、BRIC 229和2/24等CD59抗体所识别的表位相同或相近。红细胞预先接触16.3A5抗MIC 11也会降低CD59抗体BRIC 229和YTH 53.1阻断膜CD59补体抑制功能的能力。然而，单独的抗MIC 11抗体对CD59功能没有抑制作用。这可能是由于其相对较低的结合亲和力或表位特异性存在一些细微差异。使用免疫荧光的进一步研究表明，与CD59一样，缺乏糖基磷脂酰肌醇（GPI）锚定蛋白的EBV - B细胞以及特异性缺乏CD59蛋白的B细胞系中不存在MIC 11表位。总体而言，这些结果提供了强有力的证据，表明MIC 11是CD59分子上的一个决定簇。
