IDENTIFICATION AND CHARACTERIZATION OF AN EPSTEIN-BARR VIRUS-SPECIFICT-CELL RESPONSE IN THE PATHOLOGICAL TISSUE OF A PATIENT WITH HODGKINS-DISEASE

Several Lines of evidence indicate that an impairment of EBV-specific immune responses may contribute to the pathogenesis of Hodgkin's disea se (HD). At present, however, it is not clear whether a defective immu nity to EBV is a characteristic restricted to EBV-associated HD cases or a more generalized phenomenon, part of the inherent immune deficien cy of HD patients. In this study, we have addressed this issue by anal yzing EBV-specific responses in infiltrating T lymphocytes (TILs) from one HD biopsy, where the virus was confined to a small proportion of apparently normal lymphocytes. TIL cultures were established using low amounts of recombinant interleukin 2 and in the absence of specific s timulation, conditions that preferentially induce the proliferation of in vivo activated T cells. An EBV-specific cytotoxic component was re vealed by the capacity of these TILs to lyse autologous EBV-positive l ymphoblastoid cell lines (LCLs) obtained by spontaneous transformation from the lesion but not HLA-mismatched LCLs and autologous phytohemag glutinin blasts. This cytotoxic activity closely resembled that of EBV -specific memory T cells, which may be reactivated from the blood lymp hocytes of healthy donors by in vitro stimulation with autologous LCLs . The use of a panel of appropriately HLA-matched B95.8-transformed LC Ls as targets in standard Cr-51 release assays revealed EBV-specific c ytotoxic responses to be restricted mainly through the A11 and B44 HLA alleles with a minor HLA-A26-restricted component. Using autologous f ibroblasts infected with recombinant vaccinia viruses expressing the E BV latent antigens, the TIL culture was shown to recognize latent memb rane protein 2 and, to a lesser extent, EBV-encoded nuclear antigen 6. In addition, a strong proliferative response was induced by coculture of TILs with autologous but not with allogeneic LCLs or autologous ph ytohemagglutinin blasts. Six CD4-positive, EBV-specific T-cell clones were isolated by limiting dilution. The study of cytokine mRNA express ion, carried out by reverse transcriptase-assisted PCR, revealed that three of these T-cell clones expressed a Th0 phenotype, whereas 1 had a Th2 phenotype. These findings are consistent with the presence in th is HD lesion of an ongoing immune response against EBV-carrying cells and suggest that the complex immune deficiency that characterizes HD p atients probably does not include a generalized, constitutional defect of EBV-specific T-cell responses.