F-Ara increases the allogenicity of HMECs for CD8⁺ CTLs: protective effect of defibrotide.

(A) PBMCs were stimulated with irradiated HMECs in the presence of IL-2 (50 U/mL) for 7 days and were subjected to a ⁵¹Cr release assay with untreated (Control) and F-Ara (10 μg/mL)–treated HMECs (24-hour incubation) as target cells. Autolog B-LCL, autologous (effector) Epstein-Barr virus (EBV)–transformed B-lymphoblastoid cells; K 562, target cells for NK cells. Results are given as percentage specific lysis as described in “Materials and methods.” *— : percentage specific lysis of F-Ara–treated HMECs in the presence of anti-MHC class I antibody w6/32. E/T ratio: effector–target ratio. (B) Down-regulation of F-Ara–induced allogenicity of HMECs toward CD8⁺ CTLs by defibrotide (D). CD8⁺ PBMCs have been negatively selected (non-CD8⁺-cell–depleted) by magnetic bead separation. For experimental details, see legend to Figure 6A.