Complexes of heparin and platelet factor 4 specifically stimulate T cells from patients with heparin-induced thrombocytopenia thrombosis
Complexes of heparin and platelet factor 4 specifically stimulate T cells from patients with heparin-induced thrombocytopenia thrombosis
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DOI：
10.1182/blood.v94.1.208.413a06_208_215
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发表时间：
1999-07-01
期刊：
影响因子：
20.3
通讯作者：
Aster, RH
中科院分区：
文献类型：
--
作者：
Bacsi, S;De Palma, R;Aster, RH
肝素诱导的血小板减少伴血栓形成（HITT）与肝素和血小板因子4（PF 4）复合物特异性抗体相关。对HITT患者个体的研究表明，免疫球蛋白（IG）类别从IgM转变为IgG或伊加同种型。这种转变被认为需要辅助性T细胞，但还没有关于这一过程的细胞或分子基础的研究报道。为了表征HITT中的T细胞参与，在自体抗原呈递细胞（APC）的存在下，用肝素：PF 4复合物、单独的PF 4、单独的肝素和单独的培养基再刺激急性发作后不久获得的来自两名经典HITT患者的外周血单核细胞（PBMC）。然后使用“光谱分析”技术检查应答T细胞，其中扩增编码单个V β（BV）家族的CDR3结构域的序列并通过凝胶电泳分离。在与抗原（肝素：PF 4复合物）一起培养14天后，而不是在与PF 4、肝素或单独培养基一起培养后，患者细胞（而不是来自正常受试者的细胞）优先表达BV 5.1家族的含T细胞受体（TCR）的β链。BV 5.1 TCR CDR3的核苷酸测序表明，每个患者都有一个个人的库，但也有一个共同的四肽基序（PGTG）。这些发现提供了证据表明，与HITT相关的体液免疫应答是由辅助T细胞驱动的，辅助T细胞可能识别来自PF4的肽。在来自两名患者中的每一名的应答T细胞中鉴定出共同的β链CDR3基序表明，有限数量的辅助TCR可用于产生对肝素：PF 4复合物的抗体应答。TCR谱分析为研究病理性免疫反应的分子基础提供了一种新的方法，并可能有助于进一步研究HITT和其他免疫介导的血液系统疾病。(C)1999年，美国血液学会。
Heparin-induced thrombocytopenia with thrombosis (HITT) is associated with antibodies specific for complexes consisting of heparin and platelet factor 4 (PF4). Studies in individual patients with HITT have demonstrated immunoglobulin (Ig) class switching from IgM to the IgG or IgA isotypes. This transition is thought to require helper T cells, but no studies of the cellular or molecular basis of this process have yet been reported. To characterize T-cell involvement in HITT, peripheral blood mononuclear cells (PBMC) from two patients with classical HITT obtained shortly after the acute episode were restimulated with heparin:PF4 complexes, PF4 alone, heparin alone, and medium alone in the presence of autologous antigen-presenting cells (APC). Responding T cells were then examined using the technique of "spectratyping," in which sequences encoding CDR3 domains of individual V beta (BV) families are amplified and separated by gel electrophoresis. After 14 days in culture with antigen (heparin:PF4 complexes), but not after culture with PF4, heparin, or medium alone, patient cells, but not cells from normal subjects, preferentially expressed T-cell receptor (TCR)-containing beta chains of the BV 5.1 family. Nucleotide sequencing of BV 5.1 TCR CDR3 showed that each patient had a personal repertoire, but also shared a tetrapeptide motif (PGTG). These findings provide evidence that the humoral immune response associated with HITT is driven by helper T cells that presumably recognize peptides derived from PF4. Identification of a common beta-chain CDR3 motif in responding T cells from each of two patients suggests that a limited number of helper TCRs may be used to mount an antibody response to heparin:PF4 complexes. TCR spectratyping appears to offer a new way to examine the molecular basis of pathologic immune responses and may be useful in further studies of HITT and other immune mediated hemato logic disorders. (C) 1999 by The American Society of Hematology.