HIT-antibodies promote their own antigen

Abstract

Antiplatelet factor 4 (PF4) antibodies have an important role in the most frequent drug-induced immune disorder, heparin-induced thrombocytopenia (HIT). In this issue of Blood, Sachais and coworkers propose a new feature that may explain why only some anti-PF4 antibodies are pathogenic.1 In addition to epitope specificity-determining affinity and a high titer, the ability of antibodies to promote formation of their own target antigens seems to be a key factor for pathogenicity.