Vedolizumab, a humanized monoclonal antibody, targets the α4β7 integrin for treating Crohn's disease and ulcerative colitis.

Vedolizumab inhibition of high-affinity binding of MAdCAM-1 to human peripheral blood memory CD4+ T lymphocytes is tested. Peripheral blood (90 μL) is incubated with a saturating concentration (3 μg/mL) of MAdCAM-1-murine-Fc fusion protein and 4 mM MnCl2 in a final volume of 100 μL for 1 h at room temperature, in the presence or absence of vedolizumab. After washing with assay buffer, the cells are stained with fluorescentlabeled anti-mouse IgG for 15 min at room temperature. After washing again, cells are incubated with mouse serum for 10 min at room temperature, followed by staining with anti-CD4 and anti-CD45RO antibodies for 15 min at room temperature. After washing, red blood cells are lysed with BD FACS lysing solution and analyzed by flow cytometry in a FACSCalibur with CellQuest Pro software[1].