I overensstemmelse med den farmakologiske aktivitet af natalizumab viste ændringer i transporten af lymfocytter sig som en forøgelse i antallet af hvide blodlegemer såvel som en forøget miltvægt i de fleste in vivo forsøg.
Consistent with the pharmacological activity of natalizumab, altered trafficking of lymphocytes was seen as white blood cell increases as well as increased spleen weights in most in vivo studies.