Indeed, depletion of CD4+ T cells in GITRL tg mice abrogated the early increase in CD8+ T cell expansion during the first week of the infection and induced a crash of both the total CD8+ T cell pool (Fig. 7B) and the LCMV-specific CD8+ T cells at day 15 p.i. (Fig. 7C). The gene discussed is CD4; the disease is infection.