[Epidermal reticular CD1 pattern].

183 biopsies taken from various skin diseases as well as normal skin were studied in cryostat sections by means of the avidin-biotin complex immunoperoxidase technique, using monoclonal antibody anti-Leu 6, which is directed against the Langerhans cell antigen CD1. In 47 cases, we observed a reticular, pemphigus-like intercellular pattern. This pattern was neither correlated to individual skin diseases, nor to the quality or quantity of corial or epidermotropic infiltrates, nor to the HLA-DR expression of keratinocytes, nor to the count of Langerhans cells. There was, however, a correlation to the presence of Langerhans cells: This pattern was never observed in the aerosyringia or deep infundibula. We conclude, therefore, that the stained antigen has to be regarded as free CD1 derived from the Langerhans cell and diffusing into the keratinocytic intercellular spaces.