Scully Marie, Lester William A
Department of Haematology, University College London Hospital, Haematology Theme-NIHR UCLH/UCL BRC, London, United Kingdom.
Haemophilia Comprehensive Care Centre, Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom.
Hematology Am Soc Hematol Educ Program. 2024 Dec 6;2024(1):403-408. doi: 10.1182/hematology.2024000565.
Antibodies to platelet factor 4 (PF4) have been primarily linked to classical heparin-induced thrombocytopenia (cHIT). However, during the rollout of the COVID-19 vaccine program a new condition, vaccine-induced thrombocytopenia and thrombosis (VITT), was identified, related to adenoviral-based COVID-19 vaccines. The differences between these 2 conditions, both clinically and in laboratory testing, set the scene for the development of a new rapid anti-PF4 assay that is not linked with heparin (as relevant for cHIT). Concurrently, there has been a reassessment of those cases described as autoimmune HIT. Such scenarios do not follow cHIT, but there is now a clearer differentiation of heparin-dependent and heparin-independent anti-PF4 conditions. The importance of this distinction is the identification of heparin-independent anti-PF4 antibodies in a new subgroup termed VITT-like disorder. Cases appear to be rare, precipitated by infection and in a proportion of cases, orthopaedic surgery, but are associated with high mortality and the need for a different treatment pathway, which includes immunomodulation therapy.
血小板因子4（PF4）抗体主要与经典型肝素诱导的血小板减少症（cHIT）相关。然而，在新冠疫苗接种计划推行期间，一种与基于腺病毒的新冠疫苗相关的新病症——疫苗诱导的血小板减少症和血栓形成（VITT）被发现。这两种病症在临床和实验室检测方面的差异，为开发一种与肝素无关（与cHIT相关）的新型快速抗PF4检测方法奠定了基础。与此同时，对那些被描述为自身免疫性血小板减少症的病例进行了重新评估。这些情况并不符合cHIT，但现在肝素依赖性和肝素非依赖性抗PF4病症有了更明确的区分。这种区分的重要性在于在一个名为VITT样疾病的新亚组中识别出肝素非依赖性抗PF4抗体。病例似乎很罕见，由感染引发，部分病例由骨科手术引发，但与高死亡率以及需要不同的治疗途径相关，其中包括免疫调节治疗。
