CD4 and Immunodeficiency: We next examined the T cell cytokine expression profile of vaccinated and unvaccinated mice during immunodeficiency by quantifying the number of effector cytokine-producing CD4+ T cells in CD8-depleted mice (Fig. 1e, f) and the number of effector cytokine-producing CD8+ T cells in CD4-depleted mice (Fig. 1g, h).