The immune parameters matched the stroke outcome in that the PD-L1-/-, and to a lesser extent PD-L2-/- mice, had reduced levels of proinflammatory activated microglia and/or infiltrating monocytes and CD4+ T-cells in the ischemic hemispheres, thus suggesting a pathogenic rather than a regulatory role for both PD-ligands. The gene discussed is CD4; the disease is Stroke.