Comment on “Drug-Induced Thrombocytopenia: An Updated Systematic Review”

Excerpt

We have read with great interest the letter published by Dr Swisher and colleagues[1] on drug-induced thrombocytopenia. The same group have previously published similar letters to update their initial review article published in 1998.[2] However, their previous publications on drug-induced thrombocytopenia (DIT) and thrombotic thrombocytopenic purpura have failed to recognize that fluoroquinolones, a class of commonly used antimicrobials in clinical practice, can cause DIT. We recently described a patient in whom ciprofloxacin-dependent platelet-reactive IgG antibodies against glycoprotein (GP) IIb/IIIa were found.[3] A literature search identified a total of 82 cases of thrombocytopenia related to fluoroquinolone exposure. In our case report we isolated ciprofloxacin-dependent antibodies by flow cytometry and subsequently demonstrated their specificity for GPIIa/IIIb by monoclonal antibody immobilization of platelet antibodies. This suggests immune-mediated, drug-dependent destruction. Fluoroquinolones have a structural similarity with quinine, a well documented cause of DIT,[4] and we postulate that fluoroquinolones induce antibodies that bind reversibly to platelet glycoproteins such as IIb/IIIa, allowing complement-mediated opsonization and destruction of platelets in a similar manner to quinine. Fluoroquinolones have also been described to cause haemolytic anaemia, pancytopenia and hemolyticuremic syndrome and thrombotic thrombocytopenic purpura (HUS-TTP), the exact mechanism still unknown. …