What is the role of autoantibodies in post-artesunate delayed hemolysis?

Abstract

We read with great interest the recent publication by Kurth et al.1 that highlights an interesting aspect of post-artesunate delayed hemolysis (PADH) among uncomplicated malaria patients treated with oral artemisinin-based combination therapy (ACT). Post-treatment delayed hemolysis has increasingly been observed, especially among travellers from non-endemic areas.2 Besides the well-known ‘pitting’ mechanism, the article discussed that ACT might produce drug-autoantibodies that contribute to post-treatment hemolysis. We would like to discuss the possible role of autoantibodies against red blood cells (RBC) as a pathophysiologic mechanism of PADH and the clinical implication of corticosteroid therapy for patients with PADH. Camprubí et al. (2019) reported a case of PADH in a splenectomized patient with a positive direct antiglobulin test (DAT); this raised a critical discussion as the ‘pitting’ mechanism cannot explain the hemolysis in this patient.3 The phenomenon may be explained by three hypotheses involving drug-induced immune hemolytic anaemia. First, the drug, acting as a hapten, attaches to the RBC membrane and induces autoantibody reactions. Second, the immune complex mechanism involves anti-drug antibodies produced during artesunate treatment in previous infections. Once artesunate is administered in subsequent infections, a drug-anti-drug immune complex is formed and randomly binds to the RBC surface, which activates complement fixation and opsonization, leading to cell lysis. Lastly, it assumes that the drug may act as a coating for the RBCs. If IgG antibodies against the drug are present, the reaction to the drug-coated RBCs can cause hemolysis. The immune complex mechanism may explain the high levels of autoantibodies found among ‘semi-immune’ patients of African descent who developed PADH in the recent study by Kurth et al.