Characterization of CD4(-) CD8(-) CD3(+) T-cell receptor-alpha beta(+) T cells in murine cytomegalovirus infection

In this study, we have investigated that after the intraperitoneal infectio n with murine cytomegalovirus (MCMV), the CD3(+) CD4(-) CD8(-)(double negat ive; DN) T-cell receptor (TCR)alpha beta(+) T cells increased in peritoneal cavity, liver and spleen in both resistant C57BL/6 and susceptible BALB/c mice. The total cellular population of these cells showed peak levels aroun d day 5 after infection in all the three investigated organs and the follow ing phenotypical and functional characteristics emerged. The peritoneal DN TCR alpha beta(+) T cells expressed highly skewed TCRV beta 8 on day 5 afte r infection compared with the uninfected mice, but those in spleen and live r showed moderate and low skewed TCRV beta 8, respectively. The percentages of NK1.1(+) DN TCR alpha beta(+) T cells gradually decreased as did modula tion of some of their activation markers consistent with an activated cell phenotype. The peritoneal DN TCR alpha beta(+) T cells on day 5 after infec tion expressed the genes of interferon-gamma (IFN-gamma), tumour necrosis f actor-alpha, Eta-1 (early T-cell activation-1) and MCP-1 (monocyte chemoatt ractant protein 1) but lacked expression of interleukin-4 (IL-4). After in vitro stimulation with phorbol 12-myristate 13-acetate and calcium ionophor e in the presence of Brefeldin A, higher frequencies of intracellular IFN-g amma(+) DN TCR alpha beta(+) T cells were detected in all three investigate d organs of infected mice compared with those of uninfected mice. Stimulati on of peritoneal DN TCR alpha beta(+) T cells with plate-bound anti-TCR bet a monoclonal antibodies showed proliferation and also produced IFN-gamma bu t not IL-4. These results suggest that DN TCR alpha beta(+) T cells were ac tivated and may have an antiviral effect through producing IFN-gamma and so me macrophage-activating factors during an early phase of MCMV infection.