Jajosky Ryan P, Ayona Diyoly, Mener Amanda, Stowell Sean R, Arthur Connie M
Joint Program in Transfusion Medicine, Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.
Front Immunol. 2024 Nov 28;15:1475470. doi: 10.3389/fimmu.2024.1475470. eCollection 2024.
Exposure to allogenic red blood cells (RBCs), either through pregnancy or transfusion, can result in alloimmunization, which can lead to severe hemolytic transfusion reactions and pregnancy complications. Passively administered antibodies can be used to prevent alloimmunization, where steric hindrance of allogeneic epitopes has been postulated as one mechanism whereby antibody engagement may prevent RBC alloimmunization. However, the dynamics of antibody engagement on the RBC surface has remained difficult to study. To examine this, we leveraged the HOD (HEL, OVA and Duffy) model system and Fcγ receptor knockout recipients to define the dynamics of antibody engagement of the Duffy antigen in the absence of RBC clearance or antigen modulation. Using this approach, the on-rate of antibody engagement of HOD RBCs was very similar and , with high levels of antibody binding observed within minutes of HOD RBC exposure. In contrast, the off-rate of HOD RBC bound antibody was relatively slow, with appreciable dissociation not being observed for an hour. However, the dynamics of antibody interactions with HOD changed significantly when antibody decorated HOD RBCs were exposed to free antibody. Despite the presence of prebound antibody, free antibody rapidly associated with HOD RBCs, with the rate of free antibody association observed being faster than . Importantly, antibody association and dissociation occurred in the absence of any appreciable changes in RBC clearance, antigen modulation or complement deposition, suggesting that differences in antibody levels observed reflected actual differences in the dynamics of antibody binding. These results suggest that while antibodies appear to be relatively static on the cell surface once bound, antibody engagement can be quite dynamic, especially in the face of free antibody in solution. These results not only have implications in the mechanisms of antibody-mediated immunosuppression, but also the potential use of other antibody-based approaches designed to prevent hemolytic transfusion reactions or target antigens in general.
通过妊娠或输血接触异体红细胞（RBC）可导致同种免疫，进而引发严重的溶血性输血反应和妊娠并发症。被动给予的抗体可用于预防同种免疫，其中异体表位的空间位阻被认为是抗体结合可预防RBC同种免疫的一种机制。然而，抗体在RBC表面结合的动力学仍难以研究。为了对此进行研究，我们利用HOD（HEL、OVA和达菲）模型系统以及Fcγ受体敲除受体，在不存在RBC清除或抗原调节的情况下，确定达菲抗原的抗体结合动力学。使用这种方法，HOD RBC的抗体结合速率非常相似，并且在接触HOD RBC几分钟内就观察到高水平的抗体结合。相比之下，HOD RBC结合抗体的解离速率相对较慢，一小时内未观察到明显的解离。然而，当用抗体包被的HOD RBC暴露于游离抗体时，抗体与HOD相互作用的动力学发生了显著变化。尽管存在预先结合的抗体，游离抗体仍能迅速与HOD RBC结合，观察到的游离抗体结合速率比[具体数值]更快。重要的是，抗体的结合和解离发生时，RBC清除、抗原调节或补体沉积均未发生明显变化，这表明观察到的抗体水平差异反映了抗体结合动力学的实际差异。这些结果表明，虽然抗体一旦结合在细胞表面似乎相对静止，但抗体结合可能相当动态，尤其是在溶液中存在游离抗体的情况下。这些结果不仅对抗体介导的免疫抑制机制有影响，而且对旨在预防溶血性输血反应或一般靶向抗原的其他基于抗体的方法的潜在应用也有影响。
