Dendritic cells in the murine dermis in delayed-type contact hypersensitivity. An ultrastructural and immunocytochemical study

Dendritic cells within the dermis in the later stages of delayed-type contact hypersensitivity were examined ultrastructurally and immunohistochemically. The immunohistochemical observations were done using monoclonal antibody M1-8, which reacts specifically with murine Langerhans cells and interdigitating cells. Seventeen hours after challenge, infiltrating cells in the dermis included dendritic cells, possibly so-called indeterminate cells, monocytoid cells and Langerhans cells. Immunohistochemically, the indeterminate cells and some monocytoid cells were M1-8-positive. These findings suggest that indeterminate cells are intimately related to Langerhans cells, and that they belong to the mononuclear phagocyte system. M1-8 is a very useful marker for studies on the kinetics of Langerhans cells or indeterminate cells.