There is considerable interest in the potential of Epstein-Barr virus (EBV) latent antigen-specific CD4؉ T cells to act as direct effectors controlling EBV-induced B lymphoproliferations. Such activity would require direct CD4؉ T-cell recognition of latently infected cells through epitopes derived from endogenously expressed viral proteins and presented on the target cell surface in association with HLA class II molecules. It is therefore important to know how often these conditions are met. Here we provide CD4؉ epitope maps for four EBV nuclear antigens, EBNA1, -2, -3A, and -3C, and establish CD4 ؉ T-cell clones against 12 representative epitopes. For each epitope we identify the relevant HLA class II restricting allele and determine the efficiency with which epitope-specific effectors recognize the autologous EBV-transformed B-lymphoblastoid cell line (LCL). The level of recognition measured by gamma interferon release was consistent among clones to the same epitope but varied between epitopes, with values ranging from 0 to 35% of the maximum seen against the epitope peptide-loaded LCL. These epitope-specific differences, also apparent in short-term cytotoxicity and longer-term outgrowth assays on LCL targets, did not relate to the identity of the source antigen and could not be explained by the different functional avidities of the CD4 ؉ clones; rather, they appeared to reflect different levels of epitope display at the LCL surface. Thus, while CD4 ؉ T-cell responses are detectable against many epitopes in EBV latent proteins, only a minority of these responses are likely to have therapeutic potential as effectors directly recognizing latently infected target cells.

SummaryRheumatoid arthritis is a multistep disorder associated with autoimmune features of yet unknown etiology. Implication of viruses such as Epstein-Barr virus (EBV) in rheumatoid arthritis pathogenesis has been suspected on the basis of several indirect observations, but thus far, a direct link between EBV and rheumatoid arthritis has not been provided. Here we show that a large fraction of T cells infiltrating affected joints from a patient with chronic rheumatoid arthritis recognizes two EBV transactivators (BZLF1 and BMLF1) in a major histocompatibility complex-restricted fashion. Responses to these EBV antigens by synovial lymphocytes from several other chronic rheumatoid arthritis panents were readily detectable. Thus these results suggest a direct contribution of EBV to chronic rheumatoid arthritis pathogenesis. They also demonstrate for the first time the occurrence of T cell responses against EBV transactivating factors, which might be central in the control of virus reactivation.

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We recently evidenced a dramatic enrichment for T cells reactive against Epstein-Barr virus (EBV) within inflamed joints of two rheumatoid arthritis patients. To assess the generality of this phenomenon and its relevance to autoimmunity, we studied the responses of CD8 T cells from patients with either acute or chronic inflammatory diseases (rheumatoid arthritis: n = 18, ankylosing spondylitis: n = 5, psoriatic arthritis: n = 4, Reiter's syndrome: n = 3, arthrosis: n = 2, uveitis: n = 2, multiple sclerosis: n = 2, encephalitis: n = 1) against viral proteins derived from EBV and another common herpes virus, human cytomegalovirus (CMV). T cell responses against EBV and/or CMV epitopes were frequently observed within CD8 T cells derived from chronic inflammatory lesions, irrespective of their location (knee, eye, brain) and autoimmune features. In most cases, CD8 T cells derived from affected organs yielded stronger anti-viral T cell responses than CD8 T cells derived from patients' PBL, even in chronic inflammatory diseases devoid of autoimmune features or induced by defined bacterial agents. Taken together, these results suggest that the presence of virus-specific T cells within inflamed lesions of patients suffering from autoimmune diseases is a general phenomenon associated with chronic inflammation rather than the initiating cause of the autoimmune process. Since this phenomenon was sometimes associated with long-term T repertoire biases within inflamed lesions, the physiopathological significance of T cell clonal expansions found in a recurrent fashion within chronically inflamed autoimmune lesions should be interpreted with caution.