The invention relates to C5 inhibitors, which inhibit type II endothelial cell activation, wherein the inhibition is manifested by the suppression of E-selectin. These inhibitors are useful in treatment of delayed xenograft rejection or acute vascular rejection. The inhibitors include antibody molecules, as well as homologues, analogues and modified or derived forms thereof, including immunoglobulin fragments like Fab, F(ab')2 and Fv, small molecules, including peptides, oligonucleotides, peptidomimetics and organic compounds. Examples of monoclonal antibodies, which bind to and inhibit C5, were generated and are designated MAb 137-76 and MAb 137-30.