The model can also explain the seemingly contrasting conclusion that LM-specific CD8+TM recall responses become more CD4+T cell-dependent with age [67]: as opposed to the CD4+T cell-independent LCMV Arm system, Marzo et al. employed an LM infection protocol where CD4+T cell depletion greatly reduced Io CD8+TE responses [67]. The gene discussed is BMP6; the disease is infection.