Lamour A, Le Corre R, Soubrane C, Khayat D, Youinou P
Laboratory of Immunology, Brest Medical School Hospital, France.
J Autoimmun. 1996 Apr;9(2):181-91. doi: 10.1006/jaut.1996.0022.
Sera from patients with primary Sjögren's syndrome (pSS) have been examined for the presence of cell-free Fc-gamma receptor (Fc gamma R) IIIb, which is expressed in polymorphonuclear leukocytes (PMN), and the production of related autoantibody. Sera from 66 patients with pSS were evaluated by an ELISA using recombinant human Fc gamma RIIIb as the substrate and by flow cytometry. Cell-free Fc gamma RIIIb was also detected by an ELISA. The fine specificity of autoantibodies was established by inhibition with a preparation of Fc gamma RI plus Fc gamma RII, and two ELISAs using Fc gamma RI and Fc gamma RII as the substrates respectively. Anti-Fc gamma RIIIb activity was found in 30 patients (45%), but 25 of them did not react with autologous PMN, whereas they bound to Fc gamma RIIIb eluted from the same PMN in ELISA and Western blotting. Autoantibodies from one serum recognized the three receptors, six with Fc gamma RII in addition to Fc gamma RIII, and three sera were specific for the latter receptor. None of these reacted with Fc gamma RI- and Fc gamma RII-carrying cells. Cell-free Fc gamma RIIIb, but negligible amounts of Fc gamma RIIIa, were detectable in the patient sera. The membrane expression of CD15, an early activation marker, was diminished, while that of three PMN late activation markers was markedly enhanced. Taken together, these results suggest that autoantibodies are produced following the shedding of Fc gamma RIIIb upon PMN activation. A credible candidate for this activation is IgG-containing immune complexes.
对原发性干燥综合征（pSS）患者的血清进行了检测，以确定是否存在无细胞的Fc-γ受体（FcγR）IIIb（其在多形核白细胞（PMN）中表达）以及相关自身抗体的产生。使用重组人FcγRIIIb作为底物，通过酶联免疫吸附测定（ELISA）和流式细胞术对66例pSS患者的血清进行了评估。还通过ELISA检测了无细胞的FcγRIIIb。通过用FcγRI加FcγRII制剂进行抑制以及分别使用FcγRI和FcγRII作为底物的两种ELISA来确定自身抗体的精细特异性。在30例患者（45%）中发现了抗FcγRIIIb活性，但其中25例与自身PMN无反应，而它们在ELISA和蛋白质印迹法中与从相同PMN洗脱的FcγRIIIb结合。一份血清中的自身抗体识别这三种受体，6份除了FcγRIII外还识别FcγRII，3份血清对后一种受体具有特异性。这些均未与携带FcγRI和FcγRII的细胞发生反应。在患者血清中可检测到无细胞的FcγRIIIb，但FcγRIIIa的量可忽略不计。早期激活标志物CD15的膜表达降低，而三种PMN晚期激活标志物的膜表达明显增强。综上所述，这些结果表明，自身抗体是在PMN激活后FcγRIIIb脱落之后产生的。这种激活的一个可信候选物是含IgG的免疫复合物。
