New monoclonal antibody that specifically recognizes murine interdigitating and Langerhans cells

A new monoclonal antibody, M1-8, that recognizes murine interdigitating cells (IDC) and Langerhans cells was obtained from a hybridoma prepared by fusion of SP2/0 mouse myeloma cells with splenic cells of rats immunized with IDC-rich cell suspension obtained from lymph nodes of athymic nude mice (BALB/c nu/nu). The specificity was assessed immunohistochemically on frozen sections of lymph nodes and epidermal sheets from both nude and normal mice. M1-8 reacted with paracortical IDC, veiled cells of the marginal sinus, and epidermal Langerhans cells in both normal and nude mice. In simultaneous staining by M1-8 and nonspecific esterase or anti-Ia or anti-Thy-1,2 antibody, the same epidermal dendritic cells were positive for all these antigens except Thy-1,2. Immunoelectron microscopy of the lymph node suspension using gold colloid particles revealed the attachment of gold particles to the cell membrane of IDC. Analysis by flow cytometry of the lymph node cell suspension showed 14 or 6% of M1-8-positive cells in nude or normal mouse, respectively. Immunohistochemical analysis showed that M1-8 also reacted with dendritic cells in the thymus and spleen and had a different distribution from F4/80. M1-8 also reacted with monocytes in bone marrow and peripheral blood, alveolar macrophages, and thioglycollate-stimulated peritoneal exudate macrophages. The antibody belongs to the immunoglobulin M class, reacts immunochemically with a glycoprotein in the cell membrane, and has a molecular mass of approximately 15 kDa.