生物信息学预测GPIIb/IIIa抗体CTL、Th的混合表位

背景：GPIIb/IIIa是特发性血小板减少性紫癜患者最常见的血小板糖蛋白，已证实该蛋白独特型抗体结合血小板后会激活补体，破坏血小板。目的：以GPIIb/IIIa抗体为靶抗原，应用生物信息学软件对其CTL、Th细胞表位进行多参数预测。设计、时间及地点：开放性实验，于2008-03/08在珠江医院血液科实验室完成。材料：GPIIb/IIIa抗体的氨基酸序列由GENBANK公司提供。方法：分别应用SYFPEITHI，RANKPEP，BIMAS，SVMHC，PREDEP，MHCPRED，PROPRED软件对人和鼠源的血小板糖蛋白GPIIb/IIIa抗体蛋白进行HLA-A*0201，HLA-A*1101，HLA-A*2401限制性表位预测，经去除能引起自身免疫的已发表的多肽，取前者覆盖后二者的多肽为混合CTL表位，再联合软件predTAP、TAPPred的TAP结合预测结果，以及NetChop、MAPPP、PAProC软件的蛋白酶切位点预测结果，取能包含二者的多肽为CTL修正表位。用基于肽MHC-Ⅱ结合的算法Syfpeithi，RANKPEP，Mhcpred，HLAPRED进行HLA-DR的Th表位预测，最后取Th表位覆盖CTL修正表位，得到CTL、Th细胞混合表位。结果：从1 740条多肽中筛选出5条人源抗人血小板糖蛋白GPIIb/IIIa抗体的CTL、Th细胞混合表位肽，即Anti-GPIIb/ IIIa-Human的第1-15，24-38，50-64，65-81，109-121位；筛选出5条鼠源抗人血小板糖蛋白GPIIb/IIIa抗体的CTL、Th细胞混合表位肽，即Anti-GPIIb/IIIa-Mice的第1-15，26-40，46-60，68-82，93-107位。结论：根据血小板糖蛋白GPIIb/IIIa抗体预测的CTL、Th细胞优势抗原表位，可用于制备特异性抗体，可成为特发性血小板减少性紫癜新疫苗研究的靶点。

Bioinformatic prediction of CTL and Th mixed epitopes of GPIIb/IIIa antibody

BACKGROUND: GPIIb/IIIa is common platelet glycoprotein in idiopathic thrombocytopenic purpura (ITP) patients. It has been demonstrated that after the idiotype antibody of GPIIb/GPIIIa binding platelet activating complement, platelet destruction occurred in ITP patients. OBJECTIVE: Using bioinformatics approach to human platelet glycoprotein antibodies (GPIIb/IIIa) to target its CTL, Th cell epitopes in multi-parameter forecast.DESIGN, TIME AND SETTING: Open trial was performed at the laboratory of Department of Hematology, Zhujiang Hospital from May to August 2008.MATERIALS: Amino acid sequence of GPIIb/IIIa antibody was provided by Genbank.METHODS: HLA-A*0201, HLA-A*1101, and HLA-A*2401 CTL restricted epitopes of platelet membrane glycoprotein IIb/IIIa antibody of human and mice were predicted by SYFPEITHI, RANKPEP, BIMAS, SVMHC, PREDEP, MHCPRED and PROPRED predictive programs. In the results, the peptides found in HLAPRED that can lead to autoimmune disease and has been published were removed, and the epitopes of HLA-A*0201 must cover the epitopes of HLA-A*1101 and HLA-A*2401, combined to predTAP and TAPPred for predicting binding affinity of peptides toward the TAP transporter and NetChop, MAPPP, PAProc for predicting cleavages; HLA-DR Th restricted epitopes of GPIIb/IIIa antibody were predicted by SYFPEITHI, RANKPEP, MHCPRED and HLAPRED. After removing the peptides found in HLAPRED, the Th epitopes must cover the CTL mixed epitopes above, and the final epitopes were the CTL, Th mixed epitopes. RESULTS: Five peptides of CTL, Th mixed epitopes of GPIIb/GPIIIa antibody of human were selected from more than 1 740 peptides. They were located at the aa1-15, aa24-38, aa50-64, aa65-81, and aa109-121 of GPIIb/IIIa antibody-human and 5 peptides of CTL and Th mixed epitopes of GPIIb/GPIIIa antibody of mice were located at the aa1-15, aa26-40, aa46-60, aa68-82, and aa93-107 of GPIIb/IIIa antibody-mice. CONCLUSION: The mixed CTL and Th restricted epitopes of platelet membrane glycoprotein IIb/IIIa antibody can be used to prepare specific antibody, and also can become new target for the new vaccine development of ITP.