Vedolizumab, a monoclonal antibody to the gut homing α4β7 integrin, does not affect cerebrospinal fluid T-lymphocyte immunophenotype

Vedolizumab, a gut-homing α4β7 integrin antagonist, has demonstrated efficacy in ulcerative colitis and Crohn's disease. Development of progressive multifocal leukoencephalopathy, a serious brain infection associated with natalizumab (an α4β7 and α4β1 integrin antagonist), has raised concern that vedolizumab may convey a similar risk. Natalizumab is believed to impair central nervous system immune surveillance by affecting cerebrospinal fluid (CSF) lymphocyte counts and the CD4:CD8 ratio. To determine if vedolizumab elicits similar effects, we examined CSF of healthy volunteers by flow cytometry for T-lymphocyte surface markers 5 weeks after administration of intravenous vedolizumab 450 mg. No significant changes were observed in CSF T-lymphocyte populations.