GPIIIa-(49-66) is a major pathophysiologically relevant antigenic determinant for anti-platelet GPIIIa of HIV-1-related immunologic thrombocytopenia.
GPIIIa-(49-66) is a major pathophysiologically relevant antigenic determinant for anti-platelet GPIIIa of HIV-1-related immunologic thrombocytopenia.
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DOI：
10.1073/pnas.94.14.7589
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发表时间：
1997-07
影响因子：
11.1
通讯作者：
M. Nardi;Lin-Xing Liu;Simon Karpatkin
中科院分区：
文献类型：
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作者：
M. Nardi;Lin-Xing Liu;Simon Karpatkin
从免疫血小板减少性HIV-1感染者(HIV-1-ITP)血清免疫复合物中分离到高亲和力(Kd=1×10(-9)M)抗血小板GPIIIa。亲和纯化的抗血小板抗体可与重组的GPIIIa-(1-200)和-(1-66)融合多肽和18聚体的GPIIIa-(49-66)多肽反应，但不与其他7个跨越GPIIIa全长的多肽反应。大部分抗血小板抗体(约85%)可以吸附在GPIIIa-(49-66)亲和层析柱上并从其上洗脱。GPIIIa-(49-66)或等摩尔多肽-白蛋白结合物(IC50=2微米)可抑制抗体与血小板的结合。7例正常人和10例典型自身免疫性血小板减少症患者的血清与GPIIa-(49-66)呈本底反应。来自16名患者的HIV-1-ITP血清反应的平均OD值比背景值大6倍(范围从4到9倍)。血清抗GPIIa-(49-66)浓度与血小板计数呈负相关，R2=0.51，n=31，P<0.05。0001。由于小鼠血小板GPIIIa-(49-66)与人GPIIIa有83%的同源性，并且小鼠单核细胞含有人IgG1-kappa/lambda抗体的Fc受体，因此我们测定了人抗GPIIIa对小鼠血小板的体内作用。亲和纯化的抗体，25-50微克，ip，导致血小板计数急剧下降到基线的30%，4小时达到最低点，36小时恢复正常。对照组免疫球蛋白未见明显效果。急性血小板减少症可通过分别在抗体零时和抗体后2小时注射GPIIIa-(49-66)白蛋白结合物来预防或逆转，但不能通过杂乱肽-白蛋白结合物来预防或逆转。因此，HIV-1-ITP患者具有针对主要抗原决定簇GPIIIa-(49-66)的高亲和力抗血小板GPIIIa，GPIIIa-(49-66)与血小板计数呈负相关，并导致小鼠血小板减少。
High-affinity (Kd = 1 x 10(-9) M) anti-platelet GPIIIa has been isolated from serum immune complexes of immunologic thrombocytopenic HIV-1-infected patients (HIV-1-ITP). Affinity-purified anti-platelet antibody reacted with a recombinant GPIIIa-(1-200) and -(1-66) fusion peptide and with an 18-mer GPIIIa-(49-66) peptide but not with seven other GPIIIa peptides spanning the length of GPIIIa. Most of the anti-platelet antibody ( approximately 85%) could be adsorbed to and eluted from a GPIIIa-(49-66) affinity column. Binding of antibody to platelets could be inhibited by GPIIIa-(49-66) or an equimolar peptide-albumin conjugate (IC50 = 2 microM). Sera from 7 control subjects and 10 classic autoimmune thrombocytopenic patients gave background reactivity with GPIIIa-(49-66). HIV-1-ITP sera from 16 patients reacted with a mean OD 6-fold greater than background (range, 4- to 9-fold). Serum anti-GPIIIa-(49-66) concentration correlated inversely with platelet count, R2 = 0.51, n = 31, P < 0. 0001. Because mouse platelet GPIIIa-(49-66) has 83% homology with human GPIIIa and mouse monocytes contain Fc receptors for the human IgG1-kappa/lambda antibody, we determined the in vivo effect of human anti-GPIIIa on mouse platelets. Affinity-purified antibody, 25-50 microg given i.p., resulted in a precipitous drop in platelet count to 30% of baseline, with nadir at 4 hr and return to normal in 36 hr. No effect was noted with control IgG. Acute thrombocytopenia could be prevented or reversed by the injection of the GPIIIa-(49-66) albumin conjugate at zero time or 2 hr after antibody, respectively, but not with a scrambled peptide-albumin conjugate. Thus HIV-1-ITP patients have high-affinity anti-platelet GPIIIa against a major antigenic determinant, GPIIIa-(49-66), which correlates inversely with platelet count and induces thrombocytopenia in mice.