慢性特发性血小板减少性紫癜自身抗体克隆性分析

Study of the clonal characteristics of autoantibodies in chronic idiopathic thrombocytopenic purpura

目的 了解慢性特发性血小板减少性紫癜 (ITP)自身抗体克隆性生成特性。方法 采用改良的单克隆抗体免疫固定特异血小板抗原 (MAIPA)法检测 4 3例慢性ITP患者血清血小板膜糖蛋白 (GP)特异性IgG抗体及其重链亚型和轻链表型 ,采用PCR技术分析患者淋巴细胞免疫球蛋白重链基因重排。结果 4 3例中 16例 (38% )血清中至少存在一种抗GP(GPⅡb/Ⅲa、GPⅠb、GPⅠa、GPⅣ、GPⅤ )IgG抗体。 73% (8/ 11)的血清糖蛋白特异性自身抗体表现重链限制性 ,仅表达一种重链亚型 ;80 % (16 / 2 0 )的糖蛋白特异性抗体仅表达一种轻链表型 ;6例患者的糖蛋白特异性抗体既表现为轻链限制性又表现为重链限制性。PCR分析显示 ,3例存在淋巴细胞重链基因重排。结论 部分慢性ITP患者GP特异性自身抗体源于寡克隆B淋巴细胞增生。

Objective To define the clonality characteristics of autoantibodies in chronic idiopathic thrombocytopenic purpura (ITP). Methods The heavy-chain and light-chain phenotype composition of the glycoprotein (GP)-specific IgG antibodies were analysed with a modified monoclonal antibody specific immobilization of platelet antigens (MAIPA) technique. The immunoglobulin heavy-chain gene rearrangement was analysed by PCR amplification. Results 16 out of the 43 patient sera reacted with least one of the following five GPs, namely GPⅡb/Ⅲa, GPⅠb, GPⅠa, GPⅣand GPⅤ. Eight of 11(73%)GP-specific antibodies displayed a restricted heavy-chain phenotypes. 80% (16/20) of the GP-specific antibodies showed a restricted kappa or lambda light-chain phenotype. Moreover, in 6 patients the GP-specific antibodies were found to be both light-chain and heavy-chain restricte. Using PCR amplification of immunoglobulin heavy-chain genes,3 patients displayed heavy-chain genes rearrangement. Conclusion The GP-specific autoantibodies are derived from a restricted number of B-cell clones in proportion of ITP patients.