CD4 and infection: In our murine system, MusPV1 infection of the sensitive SENCAR mouse induced a dense CD4+ T cell infiltrate in the dermal and the epithelial compartment, as well as an intraepithelial one composed of CD8+ T cells, whether the animals developed papillomas as a result of the immunosuppressive CsA treatment or had clinically normal skin because they had not been immunosuppressed.