T cell cytokine synthesis at the single-cell level in BALB/c and C57BL/6 mice infected with ectromelia virus

Abstract

The purpose of the study was to evaluate synthesis of IFN-γ, IL-2, TNF-α (Th1/Tc1) and IL-4 (Th2/Tc2) at CD4+ T and CD8+ T cell level in BALB/c and C57BL/6 mice in the course of infection with ectromelia virus Moscow strain (ECTV-MOS). Synthesis of IFN-γ, IL-2, TNF-α and IL-4 in CD4+ T and CD8+ T cells in draining lymph nodes (DLNs) and spleens of BALB/c and C57BL/6 mice was detected by intracellular staining and flow cytometry analysis. Our results showed an increase in percentage of IFN-γ -synthesizing CD8+ T cells only in DLNs and spleens of C57BL/6 mice at the early stages of infection. Moreover, synthesis of IL-2 by CD4+ and CD8+ T cells occurred earlier and was stronger in C57BL/6 mice compared to BALB/c mice. The increase in TNF-α synthesis by CD4+ T and CD8+ T cells was detected mainly in DLNs of infected animals. We did not observe any changes in the percentage of IL-4-synthesizing T cells (Th2 and Tc2) during ECTV-MOS infection in both strains of mice. Results presented in this study confirmed that during the early phase of infection, C57BL/6 mice mounted a strong Th1 and Tc1 immune response against ECTV-MOS. BALB/c mice that survived the acute stage of mousepox, were able to mount an adequate cellular response to ECTV-MOS, however successful elimination of the virus in susceptible mice may occur more slowly compared to resistant strains of mice. Intracellular detection of IL-4 by flow cytometry was not sensitive enough to distinguish the differences in IL-4-synthesizing Th2 and Tc2 cells between susceptible and resistant strains of mice during ECTV-MOS infection.