Uaprasert Noppacharn, Rojnuckarin Ponlapat
Division of Hematology, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital.
Research Unit in Translational Hematology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital.
Asian Pac J Allergy Immunol. 2022 Mar 12. doi: 10.12932/AP-101121-1271.
Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a distinctive syndrome characterized by unusual site thrombosis accompanied by thrombocytopenia following adenoviral vector vaccines against severe acute respiratory syndrome coronavirus 2. Platelet-activating anti-platelet factor 4-dependent antibodies (anti-PF4 Abs) have been identified as pathogenic antibodies in almost all patients.
We proposed an immunological mechanism of VITT independent of anti-PF4 Abs.
Case report.
A 68-year-old Thai woman developed pulmonary embolism and deep vein thrombosis with thrombocytopenia one week after the second ChAdOx1 nCoV-19 vaccination with undetectable anti-PF4 Abs. The platelet count responded rapidly to intravenous immunoglobulin and steroids. Therefore, the high clinical suspicion is essential for early recognition and prompt management irrespective of anti-PF4 Ab results.
We hypothesize that platelet and endothelial activation following ChAdOx1 nCoV-19 vaccination may lead to generation of pathogenic antibodies which account for VITT independent of anti-PF4 Abs.
疫苗诱导的免疫性血栓性血小板减少症（VITT）是一种独特的综合征，其特征是在接种针对严重急性呼吸综合征冠状病毒2的腺病毒载体疫苗后，出现不寻常部位的血栓形成并伴有血小板减少。血小板活化的抗血小板因子4依赖性抗体（抗PF4抗体）已被确定为几乎所有患者的致病抗体。
我们提出了一种独立于抗PF4抗体的VITT免疫机制。
病例报告。
一名68岁泰国女性在第二次接种ChAdOx1 nCoV-19疫苗一周后出现肺栓塞、深静脉血栓形成和血小板减少，抗PF4抗体检测不到。血小板计数对静脉注射免疫球蛋白和类固醇迅速反应。因此，无论抗PF4抗体结果如何，高度的临床怀疑对于早期识别和及时处理至关重要。
我们推测，接种ChAdOx1 nCoV-19疫苗后血小板和内皮细胞的激活可能导致致病抗体的产生，这是导致VITT的原因，且独立于抗PF4抗体。
