FIG. 5.

Reduced T-cell responses in the lungs of SARS-CoV-infected mice depleted of CD4⁺ T cells. Mice were treated with isotype control and MAbs against T-cell subsets as described in Materials and Methods. (A) Cytokines and chemokines were determined in lung homogenates by Cytokine Beads Array and Bioplex on day 7 p.i. Data are shown as means ± SEMs for four mice. (B) Number of cells isolated from the lungs of mice treated with MAbs for FACS analysis by day 9 p.i. Data are presented as means ± SEMs for four mice from a typical experiment. (C) Intracellular staining for IFN-γ on CD4⁺ and CD8⁺ T cells isolated from the lungs by day 9 p.i., with ex vivo stimulation with SARS-CoV antigen. Data are presented as means ± SEMs for four mice. (D) FACS analysis of CD107 expression on IFN-γ-negative (subset A) and IFN-γ-positive (subset B) T cells isolated from the lungs on day 9 p.i., with ex vivo stimulation with viral antigen. The recorded numbers denote the percentages of IFN-γ-positive CD4⁺ or CD8⁺ T cells expressing CD107.