Characteristics of human EBV-specific cytotoxic T lymphocytes utilized for adoptive immunotherapy of EBV-induced lymphoproliferations in xenografted SCID mice.

Human Epstein-Barr virus-specific cytotoxic T lymphocytes (EBV-CTLs) prolong the survival of mice with severe combined immune deficiency bearing the autologous, but not HLA-mismatched, human EBV-induced lymphoproliferative disorders (EBV-LPDs). In the present study, we demonstrate that the HLA-restricted activity displayed by EBV-CTLs both in vitro and in vivo correlates with their in vivo homing pattern, and further characterize these effectors. EBV-CTLs were CD3+, CD16/56-, TCR alpha/beta+, predominantly CD8+ and CD4-, and had a high expression of T-cell activation antigens. EBV-CTLs were positive for CD11a/CD18, CD54, CD58, CD44, CD49d, CD28, and CD45RO, and negative for CD45RA, CD11b, CD11c. After 26 days in culture, EBV-CTLs displayed strong cytotoxicity against the autologous EBV-transformed B-cell line (EBV-LCL), which was inhibited by the addition of anti-CD3 MoAb and mostly HLA class I-restricted. Unirradiated and irradiated EBV-CTLs in the absence of IL-2 failed to proliferate after more than 2 days in culture with the autologous EBV-LCLs, while unirradiated EBV-CTLs with IL-2 formed large colonies and had a high thymidine incorporation both on days 5 and 8. The cytotoxicity of irradiated EBV-CTLs against the autologous EBV-LCLs was conserved. It remains to be determined whether irradiated EBV-CTLs are capable of homing to EBV-LPDs in vivo and to mediate a therapeutic response comparable to that observed with unirradiated EBV-CTLs.