TISSUE DISTRIBUTION OF THE DEC-205 PROTEIN THAT IS DETECTED BY THE MONOCLONAL-ANTIBODY NLDC-145 .1. EXPRESSION ON DENDRITIC CELLS AND OTHERSUBSETS OF MOUSE LEUKOCYTES

Prior studies by a variety of groups demonstrated that the mAb NLDC-14 5 reacted primarily with dendritic cells (DCs) and the epithelial cell s of the thymic cortex. We recently reported that this mAb recognizes DEC-205, a 205-kDa integral membrane glycoprotein with a unique amino- terminal sequence, and raised a rabbit polyclonal antibody to purified DEC-205 with higher affinity for the blotted antigen than the origina l mAb. Here we utilize both the polyclonal and NLDC-145 to reassess th e expression and function of DEC-205 on leukocytes. By cytofluorograph y, DCs derived from the epidermis (Langerhans cells) and from prolifer ating bone marrow progenitors (BMDCs) expressed high levels (2-3 logs) of DEC-205, while freshly isolated spleen DCs comprised two subsets, most (80%) staining at low levels (less than or equal to 1 log), the r emainder moderately (1.5 logs). DEC-205 epitopes were sensitive to try psin, but were regenerated in culture. Resident and inflammatory perit oneal macrophages did not express the antigen, except for small amount s on thioglycollate-elicited cells. B cells from spleen, lymph node, b one marrow, blood, and peritoneal fluid expressed levels of DEC-205 th at were 10- to 50-fold lower than those on BMDCs. Marrow pro- and pre- B cells did not express DEC-205. Polyclonal anti-DEC-205 failed to inh ibit either stimulation of a primary mixed leukocyte reaction by DCs i n vitro, or a local graft vs host response in vivo, where parental T c ells were injected into F1 mice. DEC-205 is therefore more broadly exp ressed on leukocytes than previously appreciated, but its function rem ains unclear. (C) 1995 Academic Press, Inc.