Bettaieb A, Oksenhendler E, Duedari N, Bierling P
Laboratoire d'Immunologie Leuco-Plaquettaire, Centre de Transfusion, Créteil, France.
Clin Exp Immunol. 1996 Jan;103(1):19-23. doi: 10.1046/j.1365-2249.1996.917606.x.
We have previously demonstrated that immune platelet destruction observed in an AIDS-free HIV-infected patient was associated with the presence of a cross-reactive antibody recognizing both HIV-glycoprotein (gp)120 and platelet gpIIIa (CD61). We have now investigated the presence of such antibodies in other HIV-infected patients, together with the molecular structure of the cross-reactive epitope. Platelet gpIIb/IIIa antibodies were characterized in sera from HIV-infected patients with immune thrombocytopenic purpura by means of an ELISA and a radio-immunoprecipitation procedure (RIP). The platelet antibodies were purified and tested for their ability to recognize HIV-gp. We also tried to characterize the antibody target epitope on HIV-gp120 using recombinant gp and synthetic peptides. IgG with anti-gpIIb/IIIa activity were detected, by means of an ELISA with purified gpIIb/IIIa, in 101/138 (73%) sera from HIV-infected patients with immune thrombocytopenic purpura. The platelet antibodies were purified from 23 sera by absorption/elution on purified immobilized platelet gpIIb/IIIa, and recognition of gpIIIa was confirmed in eight cases with a RIP. Furthermore, the presence of a cross-reactive antibody between HIV-gp120 and platelet gpIIIa was demonstrated in 18/18 patients (including the eight with a confirmed gpIIIa antibody) by the ability of the serum HIV-gp160/120 antibodies to bind to purified gpIIb/IIIa. The cross-reactive epitope was shown to be independent of the carbohydrate moieties of gp120, since deglycosylation of two recombinant (r)-gp120s did not abolish antibody binding. However, the antibody did not recognize synthetic gp120 peptides spanning 355 of the 516 amino acids of gp120, particularly the four regions exhibiting sequences of four or five consecutive amino acids that are identical between r-gp120 and gpIIIa. Our results thus support the hypothesis that the cross-reactive antibody recognizes the conformational structure of gp120. These results strongly suggest that molecular mimicry between HIV-gp120 and platelet gpIIIa may be important in the pathogenesis of immune thrombocytopenia in AIDS-free HIV-infected patients.
我们之前已经证明，在一名未患艾滋病的HIV感染患者中观察到的免疫性血小板破坏与一种能识别HIV糖蛋白（gp）120和血小板gpIIIa（CD61）的交叉反应性抗体的存在有关。我们现在研究了其他HIV感染患者中此类抗体的存在情况，以及交叉反应性表位的分子结构。通过酶联免疫吸附测定（ELISA）和放射免疫沉淀法（RIP）对患有免疫性血小板减少性紫癜的HIV感染患者血清中的血小板gpIIb/IIIa抗体进行了鉴定。纯化血小板抗体并检测其识别HIV-gp的能力。我们还尝试使用重组gp和合成肽来鉴定HIV-gp120上的抗体靶表位。通过使用纯化的gpIIb/IIIa进行ELISA检测，在138例患有免疫性血小板减少性紫癜的HIV感染患者的101份（73%）血清中检测到了具有抗gpIIb/IIIa活性的IgG。通过在纯化的固定化血小板gpIIb/IIIa上进行吸附/洗脱，从23份血清中纯化出了血小板抗体，并用RIP在8例患者中证实了对gpIIIa的识别。此外，通过血清HIV-gp160/120抗体与纯化的gpIIb/IIIa结合的能力，在18/18例患者（包括8例已证实有gpIIIa抗体的患者）中证明了HIV-gp120与血小板gpIIIa之间存在交叉反应性抗体。交叉反应性表位被证明独立于gp120的碳水化合物部分，因为两种重组（r）-gp120的去糖基化并没有消除抗体结合。然而，该抗体不能识别跨越gp120 516个氨基酸中355个氨基酸的合成gp120肽，特别是不能识别r-gp120和gpIIIa之间具有四个或五个连续相同氨基酸序列的四个区域。因此，我们的结果支持了交叉反应性抗体识别gp120构象结构的假说。这些结果强烈表明，HIV-gp120与血小板gpIIIa之间的分子模拟在未患艾滋病的HIV感染患者免疫性血小板减少症的发病机制中可能很重要。
