TISSUE DISTRIBUTION OF THE DEC-205 PROTEIN THAT IS DETECTED BY THE MONOCLONAL-ANTIBODY NLDC-145 .2. EXPRESSION IN-SITU IN LYMPHOID AND NONLYMPHOID TISSUES

The rat monoclonal antibody NLDC-145, which has been utilized as a mar ker for mouse dendritic cells in numerous studies, binds an antigen th at is more broadly distributed, This antigen is a unique 205-kDa integ ral membrane glycoprotein called DEC-205, which we have recently purif ied in quantities sufficient for basic biochemical studies, N-terminal sequencing, and immunization of rabbits. In cytofluorographic experim ents, both the new polyclonal antibody and the original monoclonal det ected DEC-205 on many classes of nondendritic murine leukocytes, parti cularly B cells. The quantities of DEC-205 on the surfaces of these ce lls were 10 to 50 times lower than those on epidermal and bone marrow dendritic cells. Here we utilize these reagents to reassess the tissue distribution of DEC-205 by immunohistochemical staining of frozen sec tions from a variety of organs, and by multiple-organ immunoblotting. Abundant expression of DEC-205 was confirmed histologically on thymic and intestinal epithelia and on dendritic cells in the T cell areas of peripheral lymphoid organs. In addition, DEC-205 was visualized in se veral other locations: B lymphocytes within B cell follicles, the stro ma of the bone marrow, the epithelia of pulmonary airways, and the cap illaries of the brain. Immunoblotting confirmed the presence of substa ntial levels of DEC-205 protein in lysates prepared from lymphoid tiss ues and from lung, marrow, and intestine. Thus, while DEC-205 is expre ssed at high levels by dendritic cells, it is also expressed by a numb er of other cell types in situ. (C) 1995 Academic Press, Inc.