Adhesion of lymphocytes to glomerular endothelial cells might be a critical step in the development of acute and chronic glomerulonephritis. The protective effect of anti-CD11a and anti-intercellular adhesion molecule (ICAM-1) antibodies on the cytotoxity elicited by phorbol 12-myristate 13-acetate (PMA)-stimulated lymphocytes was investigated by using cultured bovine glomerular endothelial cells (GEN). Both anti-CD11a and CD18 antibodies inhibited GEN injury induced by the activated lymphocytes in a dose-dependent manner. In addition, both antibodies also inhibited the adhesion of the activated lymphocytes to the GEN monolayers. These results suggest that it is important for activated lymphocytes to bind to GEN via adhesion molecules for cytotoxity to be produced by the activated lymphocytes.