ISOLATION AND CHARACTERIZATION OF CDNA FOR THE SSBIL2 AUTO ANTIGEN

风湿病自身抗体靶点SSB/La抗原的分子结构及基因表达模式从lambdagt11-cDNA文库中克隆到SSB/La的cDNA。分离得到的SSB/La cDNA作为杂交探针。用各种限制性内切酶对外周血单核细胞DNA进行酶切，检测基因多态性的存在。虽然在Ku基因中观察到RFLP，但在SSB/La抗原中未检测到遗传多态性。比较有SSB/La自身抗体的患者和无SSB/La自身抗体的患者以及正常对照组中SSB/La抗原特异性mRNA的数量。SSB/La自身抗体患者SSB/La mRNA明显升高。结合我们之前的研究结果，包括高滴度的SSB/La抗体，限制性b细胞克隆产生抗SSB/La，以及交叉反应独特型的罕见发生，本研究的结果表明，长时间的抗原刺激可能参与了SSB/La自身抗体的产生。

The molecular structures and modes of gene expression of the SSB/La antigen which is the target of autoantibodies in rheumtic diseases. The cDNA of the SSB/La was cloned from the lambdagt11-cDNA library. The isolated SSB/La cDNA was used as the hybridization probe.The peripheral blood mononuclear cell DNA was digested by various restriction enzymes and examined for the presence of the genetic polymorphism. Although the RFLP was observed for the Ku gene, genetic polymorphism was not detected for the SSB/La antigen.The amount of mRNA specific for the SSB/La antigen was compared among the patients with and without autoantibodies to the SSB/La as well as normal controls. There were definite increase of the SSB/La mRNA in patients with autoantibodies to the SSB/La.Combined with our previous findings which includes high titer antibodies to the SSB/La, production of the anti-SSB/La by restricted B-cell clones, and rare occurences of cross reactive idiotypes, the results of the present study suggest that the prolonged antigenic stimulation might be involved in the production of the autoantibodies to the SSB/La.