Immediate transient thrombocytopenia at the time of alemtuzumab infusion in multiple sclerosis.

Background: Alemtuzumab is a monoclonal antibody approved for relapsing-remitting multiple sclerosis (RRMS). Although Immune thrombocytopenia (ITP) has been reported as a secondary autoimmune phenomenon following alemtuzumab infusion, immediate thrombocytopenia during the infusion has not been reported.

Objective: We report transient, reversible, self-limiting acute-onset thrombocytopenia during the first course with alemtuzumab.