近日，加拿大麦克马斯特大学Ishac Nazy团队研究了单克隆抗体在肝素诱导的血小板减少症发病机制中的作用。该项研究成果发表在2025年9月4日出版的《新英格兰医学杂志》上。

肝素诱导的血小板减少症（HIT）是一种免疫介导的血小板疾病，由靶向血小板因子4 （PF4）和肝素复合物的抗体引起。HIT的特征是一种多克隆免疫反应；然而，其他罕见的抗PF4疾病的研究已经发现了克隆限制性抗体。

课题组研究了致病性HIT抗体的克隆性。从9例临床和血清学证实的HIT患者的血清样本中，使用PF4-肝素珠对PF4-肝素抗体进行亲和纯化。采用免疫固定电泳和质谱法测定抗体的克隆性。用酶免疫分析法评估抗体与PF4的结合，用P-选择素表达法评估功能性血小板活化。利用PF4突变文库绘制了两例患者的HIT抗体表位。

所有9例HIT患者的血清样品经酶免疫测定和P-选择素表达测定均为PF4-肝素血小板活化抗体阳性，6例（67%）样品经免疫固定电泳检测为单克隆抗体。在P-选择素表达试验中，所有9个样品的PF4-肝素亲和纯化抗体激活血小板，质谱分析显示单克隆。亲和纯化后，抗体缺失的血清样品在酶免疫试验中失去结合活性，在P-选择素表达试验中失去功能活性，证实了致病抗体的去除。血清样品中抗PF4 -肝素抗体所靶向的PF4抗原表位与亲和纯化单克隆抗体所靶向的表位相同。

研究结果表明，9例HIT患者的致病抗体均为单克隆。这一发现为HIT的发病机制提供了深入的了解，并对改进诊断和靶向治疗具有重要意义。

附：英文原文

Title: Monoclonal Antibodies in the Pathogenesis of Heparin-Induced Thrombocytopenia

Author: Jared Treverton, Donald M. Arnold, Daniil G. Ivanov, Nikola Ivetic, Yi Zhang, Hossam A. Ali, Rumi Clare, Igor A. Kaltashov, John G. Kelton, Ishac Nazy

Issue&Volume: 2025-09-04

Abstract:

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is an immune-mediated platelet disorder caused by antibodies that target complexes of platelet factor 4 (PF4) and heparin. HIT has been characterized as a polyclonal immune response; however, studies of other rare anti-PF4 disorders have identified clonally restricted antibodies.

METHODS

In this study, we investigated the clonality of pathogenic HIT antibodies. Antibodies against PF4–heparin were affinity-purified with the use of PF4–heparin beads from serum samples obtained from nine patients with clinically and serologically confirmed HIT. Antibody clonality was assessed by means of immunofixation electrophoresis and mass spectrometry. Antibody binding to PF4 was evaluated by an enzyme immunoassay, and functional platelet activation was evaluated with the use of a P-selectin expression assay. HIT antibody epitopes were mapped in two patients with the use of a PF4 mutant library.

RESULTS

Serum samples from all nine patients with HIT were positive for platelet-activating antibodies against PF4–heparin by enzyme immunoassay, as well as the P-selectin expression assay, and six samples (67%) had a monoclonal antibody detectable by immunofixation electrophoresis. The affinity-purified antibodies against PF4–heparin from all nine samples activated platelets in the P-selectin expression assay, and mass spectrometry showed monoclonality. After affinity purification, antibody-depleted serum samples lost binding activity in the enzyme immunoassay and functional activity in the P-selectin expression assay, which confirmed the removal of the pathogenic antibodies. The epitopes on PF4 targeted by anti–PF4–heparin antibodies from serum samples were the same as those targeted by the affinity-purified monoclonal antibodies.

CONCLUSIONS

The pathogenic antibodies in all nine patients with HIT were found to be monoclonal. This finding provides insight into the pathogenesis of HIT and has implications for improved diagnostics and targeted therapeutics.

DOI: NJ202509043930908

Source: https://www.nejm.org/doi/full/10.1056/NEJMoa2507175