Thrombocytopenia after second exposure to abciximab is caused by antibodies that recognize abciximab-coated platelets.

Thrombocytopenia, often severe, occurs in 1% to 2% of patients given the fibrinogen receptor antagonist abciximab, a chimeric Fab fragment containing murine specificity-determining and human framework sequences. The cause of this complication has not yet been defined. Studies of 9 patients who developed profound thrombocytopenia (platelets <10 x 10(9)/L [10 000/microL]) within a few hours of being given abciximab a second time showed that each had a strong immunoglobulin G (IgG) antibody that recognized platelets sensitized with abciximab.