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Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that affects multiple organs, and its pathogenesis is known to involve many cell types of the adaptive immune systems. The exact cause of lupus remains a mystery. Previous studies suggested that virus infection, such as human cytomegalovirus (HCMV), is a possible etiology leading to SLE. HCMV infection could increase the risk in the development of SLE. HCMV is known to induce autoimmune diseases in mice. We have revealed that adult SLE patients have elevated anti-HCMV-pp65-AA336-439 activity. Therefore, viral B cell epitope(s) that exacerbates the break down of tolerance could have located on this region. B cells are first described as high efficient antigen-presenting cells (APC) of autoimmune disease as early as 20 years ago. Compare to other APC that take up antigen by nonspecific transport mechanisms, B cells trap antigens through membrane-associated, antigen-specific receptor (i.e. B cell receptor [BCR]) and present antigens to CD4 T cells provoking immune response. In this study, two pp65 subfragments, AA336-439 and AA336-379, were cloned into pcDNA3.0 to generate DNA vaccines and both constructs were used as vaccines to induce immune response in BALB/c mice. Following immunizations with plasmids, mice were challenged with AA336-439 and AA366-379 proteins respectively to boost humoral reactivity. Splenocytes were isolated and treated with full length pp65 to mimic the immune responses and antigen uptake through BCR. The aim is intended to reveal the mimitope that induces B cell activation and the role of activated antigen-specific B cells in triggering autoimmunity. The reactivity of both CD4+ and CD8+ lymphocyte to pp65 antigen and kidney lysate were studied. The results showed that AA336-439 not only induced immune responses to few Hela antigens but also armed B cell to response to lysate from kidney via IL-10 secretion.
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