This study has enabled us to identify the influence of the chemokine, macrophage inflammatory protein-1alpha (MIP-1alpha), on leukocyte behavior at the blood-retina barrier in vivo and its link with the inflammatory process and disease pathogenesis. MIP-1alpha has not previously been thought to be effective under conditions of physiological shear flow. However, short-term anti-MIP-1alpha treatment inhibited leukocyte slowing and accumulation and subsequent extravasation of leukocytes at the blood-retina barrier in animals with experimental autoimmune uveoretinitis. This was effective predominantly in the post-capillary venules which have been shown to be the main site of passage of leukocytes across the blood-retina barrier. Long-term anti-MIP-1alpha treatment also prevented decreased leukocyte velocity and reduced disease severity as measured clinically, histologically and in terms of blood-retina barrier breakdown.