Thy 1+ Asialo GM1+ Dendritic Epidermal Cells in Skin Defense Mechanisms of Vaccinia Virus-infected Mice

To define different growths of vaccinia virus (VV) in the footpad, ear and tail skin of ddY and BALB c mice, we investigated the roles of Ia+ Langerhans cells (LC) and Ia- dendritic epidermal cells (DEC) in the skin defense mechanisms. With respect to LC obtained from the footpad, ear and tail skin of BALB/c mice, the level of lysosomal enzyme, phagocytic, antigen-presenting and antiviral activities were almost the same. Footpad DEC exhibited higher natural killer (NK)-like lysis activity against YAC-1 target cells than ear and tail DEC. The NK-like lysis activity of footpad DEC was also seen in athymic nude mice (BALB/c nu/nu) but not in NK cell-defective beige mice (C57BL/6 bg/bg). The footpad DEC activity was completely abolished by in vitro and in vivo treatment with anti-Thy 1.2 or anti-asialo GM1 antibody, and VV replicated in the footpad 10(3) fold more than in the untreated group, but not by treatment with anti-Iad antibody. When footpad Thy 1.2+ asialo GM1+ DEC were adoptively transferred to the tail skin of syngeneic mice, followed by intradermal challenge of the mice with VV, viral replication in the tail skin was markedly suppressed. These results indicated that the pathogenicity of VV in the skin is affected by Thy 1.2+ asialo GM1+ DEC rather than by Ia+ LC.