Protective effects of CD8+ CTLs from influenza-infected mice. Splenic lymphocytes from Balb/c mice surviving A/Taiwan (H1N1) infection were stimulated with vaccinia-NP and vaccinia-gp120, respectively, for 5 days. CD8+ and CD8- cells (CD4+ T cells, B cells and macrophages) were obtained using AutoMacs. 1 × 107 cells were injected into the tail vein of the mice (6 per group). Four hours later, they were challenged by intranasal inoculation of 200 MID50 of influenza A/HK68 virus. Virus in the lung, nasal turbinate and nasal wash was measured 8 days later. * P < 0.005. Values are GMT log10/ml of lung or nasal turbinate homogenate ± SEM.