T cell Epitopes of the La/SSB autoantigen in humanized transgenic mice expressing the HLA class II haplotype DRB1*0301/DQBI*0201
T cell Epitopes of the La/SSB autoantigen in humanized transgenic mice expressing the HLA class II haplotype DRB1*0301/DQBI*0201
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DOI：
10.1002/art.22870
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发表时间：
2007-10-01
影响因子：
--
通讯作者：
Farris, A. Darise
中科院分区：
文献类型：
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作者：
Dudek, Nadine L.;Maier, Shannon;Farris, A. Darise
目标。T细胞参与产生抗la /SSB和抗ro /SSA自身抗体，这些抗体通常与系统性红斑狼疮和干燥综合征的DR3/DQ2单倍型相关。本研究旨在探讨DR3/ dq2限制性T细胞对野生型人hLa （hLa）和截断型突变hLa的反应。用重组抗原免疫表达HLA-DRB1*0301/DQB1*0201 （DR3/DQ2）的人源化转基因小鼠，检测其自身抗体的产生和T细胞对La自身抗原重叠肽的增殖。用阻断性单克隆抗体和直接结合试验确定了HLA限制性和鉴定的T细胞表位与DR3或DQ2的肽结合。DR3/ dq2转基因小鼠在hLa蛋白免疫后对hLa产生了异常快速的类转换体液反应，其特征是扩散到Ro 52和Ro 60蛋白。hLa中的7个T细胞决定因子仅限于hLa - dr3 /DQ2单倍型。测试的6个表位仅限于HLA-DR和与半服务DR3结合基序结合的DR3。尽管在某些情况下具有有效的DQ结合活性，但这些表位没有DQ限制。突变体La未发现新t细胞表位；然而，与hLa引发的T细胞相比，突变La引发的T细胞对hLa表位（151-168）的增殖显著增加。已鉴定出hLa的多个dr3限制性表位。这些发现表明，体细胞突变或可能的颗粒酶b介导的裂解产生的La的截断改变了T细胞对hLa反应的免疫优势等级，并可能是启动或维持抗La自身免疫的一个因素。
Objective. T cells are implicated in the production of anti-La/SSB and anti-Ro/SSA autoantibodies commonly associated with the DR3/DQ2 haplotype in systemic lupus erythematosus and Sjogren's syndrome. This study was undertaken to investigate the DR3/DQ2-restricted T cell response to wild-type human La (hLa) and a truncated form of mutant La.Methods. Humanized transgenic mice expressing HLA-DRB1*0301/DQB1*0201 (DR3/DQ2) were immunized with recombinant antigen and examined for development of autoantibodies and T cell proliferation against overlapping peptides spanning the La autoantigen. HLA restriction and peptide binding of identified T cell epitopes to DR3 or DQ2 were determined using blocking monoclonal antibodies and a direct binding assay.Results. DR3/DQ2-transgenic mice generated an unusually rapid class-switched humoral response to hLa with characteristic spreading to Ro 52 and Ro 60 proteins following hLa protein immunization. Seven T cell determinants in hLa were restricted to the HLA-DR3/DQ2 haplotype. Six epitopes tested were restricted to HLA-DR and bound DR3 with semiconserved DR3 binding motifs. No DQ restriction of these epitopes was demonstrable despite efficient DQ binding activity in some cases. No neo-T cell epitopes were identified in mutant La; however, T cells primed with mutant La exhibited a striking increase in proliferation to the epitope hLa(151-168) compared with T cells primed with hLa.Conclusion. Multiple DR3-restricted epitopes of hLa have been identified. These findings suggest that truncation of La produced by somatic mutation or possibly granzyme B-mediated cleavage alters the immunodominance hierarchy of T cell responsiveness to hLa and may be a factor in the initiation or maintenance of anti-La autoimmunity.