The data indicate that IVIg provides a two-way protective mechanism for cerebral endothelial cells, firstly by blocking the increase in BBB permeability involving downregulation of tight-junction proteins claudin 5 and occludin, and secondly by preventing ischemia-induced endothelial cell death involving a reduction in anti-apoptotic proteins, Bcl-2 and Bcl-XL. The gene discussed is BCL2L1; the disease is ischemia.