Recipients producing posttransplant HLA antibodies (Ab) are at a higher risk for acute and chronic Ab-mediated rejection (AMR). Donor endothelial cells (EC) lining the blood vessels of the allograft are the primary targets of AMR. Angiogenesis and neovascularization are considered to be hallmarks of chronic rejection and transplant-associated vasculopothy (TAV). Angiogenesis is a multistep process of EC activation including proliferation and migration. This study investigated the potential for anti-class II Ab to contribute to the process of angiogenesis by stimulating EC activation and migration. HLA-II expression was induced in primary human aortic EC by recombinant adenovirus pAd/PL-DEST encoding CIITA (Ad-CIITA), HLA-II transactvator, or treatment with TNFa and IFNg. HLA-II expression was determined by flow cytometry. Class II+ EC were stimulated with anti-HLA-II Ab and protein phosphorylation was detected by Western Blot. Class II induced cell migration was assessed by wound healing using phase contrast microscopy. Ligation of HLA-II antigens on cytokine pretreated or Ad-CIITA infected EC stimulated a marked increase in phosphorylation of Src, PI3K and a concomitant inactivation of TSC2. Stimulation with anti-class II Ab also mediated activation of mTORC1 pathway including increased phosphorylation of S6K and S6RP, and the mTORC2-targets Akt and ERK. EC stimulated with HLA-II Ab migrated across the wound and closed the gap whereas in the presence of pharmacological inhibitors targeting Src, PI3K, ERK, and TSC/mTOR, HLA-II Ab-induced cell migration was abolished. We report for the first time that Ab ligation of HLA-II molecules expressed on EC stimulates a series of intracellular signals culminating in EC migration. HLA-II–mediated transduction of signals is most likely of importance in the setting of chronic AMR, in which Ab-mediated modifications of endothelial cell function are thought to promote angiogenesis and neovascularization contributing to TAV.