Contribution of herpesvirus specific CD8 T cells to anti-viral T cell response in humans

Herpesviruses infect most humans. their infections can be associated with pathological conditions and significant changes in t cell repertoire but evidences of symbiotic effects of herpesvirus latency have never been demonstrated. we tested the hypothesis that hcmv and ebv-specific cd8 t cells contribute to the heterologous anti-viral immune response. volume of activated/proliferating virus-specific and total cd8 t cells was evaluated in 50 patients with acute viral infections: 20 with hbv,12 with dengue,12 with influenza,3 with adenovirus infection and 3 with fevers of unknown etiology. virus-specific (ebv,hcmv,influenza) pentamer+ and total cd8 t cells were analyzed for activation (cd38/hla-dr),proliferation (ki- 7/bcl- 2low) and cytokine production. we observed that all acute viral infections trigger an expansion of activated/proliferating cd8 t cells,which differs in size depending on the infection but is invariably inflated by cd8 t cells specific for persistent herpesviruses (hcmv/ebv). cd8 t cells specific for other non-related non persistent viral infection (i.e. influenza) were not activated. il-15,which is produced during acute viral infections,is the likely contributing mechanism driving the selective activation of herpesvirus specific cd8 t cells. in addition we were able to show that herpesvirus specific cd8 t cells displayed an increased ability to produce the anti-viral cytokine interferon-c during the acute phase of heterologous viral infection. taken together,these data demonstrated that activated herpesvirus specific cd8 t cells inflate the activated/ proliferating cd8 t cells population present during acute viral infections in human and can contribute to the heterologous anti-viral t cell response. © 2010 sandalova et al.