Similarly the ability of the CD103+ RDC to preferentially stimulates naïve CD8+ T cells is unlikely to be directly related to the localization of this RDC subset in the respiratory tract and their accessibility of viral antigen, since both the CD103+ and CD11bhi RDC can capture viral antigen produced by either natural infection or vaccine installation in the respiratory tract and efficiently present in vivo processed antigen to naive CD4+ T cells. The gene discussed is CD4; the disease is infection.