Autoimmune hemolytic anemia, demyelinating relapse, and AQP1 antibodies after alemtuzumab infusion

Abstract

Autoimmune hemolytic anemia (AIHA) has been reported after treatment with an anti-CD52 monoclonal antibody (alemtuzumab) in 7 MS cases.1 All underwent positive direct Coombs test, i.e., antibodies to red blood cells (RBCs); however, no autoantibody (Ab) specificity was identified.1 Aquaporin 1 (AQP1), expressed in RBCs2 and human astrocytes,3,4 has been linked with autoimmunity: in some AIHA cases (Abs to Colton group antigens located on AQP1)2 and in some patients with CNS demyelinating disorders.3,4 Therefore, AQP1-Abs deserve investigation as the possible linking cause of the concurrent presence of the 2 disorders. Here, we present a patient characterized with MS, however, with extensive longitudinal transverse myelitis (LETM), who developed AIHA in parallel with brain demyelinating relapse, 1 year after alemtuzumab infusion; interestingly, a high AQP1-Ab titer was detected, which dropped in parallel with patient recovery.