Expression of human DEC-205 (CD205) multilectin receptor on leukocytes

Abstract

DEC-205 (CD205) belongs to the macrophage mannose receptor family of C-type lectin endocytic receptors and behaves as an antigen uptake/ processing receptor for dendritic cells (DC). To investigate DEC-205 tissue distribution in human leukocytes, we generated a series of anti-human DEC-205 monoclonal antibodies (MMRI-5, 6 and 7), which recognized epitopes within the C-type lectin-like domains 1 and 2, and the MMRI-7 immunoprecipitated a single ∼200 kDa band, identified as DEC-205 by mass spectrometry. MMRI-7 and another DEC-205 mAb (MG38), which recognized the epitope within the DEC-205 cysteine-rich and fibronectin type II domain, were used to examine DEC-205 expression by human leukocytes. Unlike mouse DEC-205, which is reported to have predominant expression on DC, human DEC-205 was detected by flow cytometry at relatively high levels on myeloid blood DC and monocytes, at moderate levels on B lymphocytes and at low levels on NK cells, plasmacytoid blood DC and T lymphocytes. MMRI-7 F(ab′)2 also labeled monocytes, B lymphocytes and NK cells similarly excluding reactivity due to non-specific binding of the mAb to FcγR. Tonsil mononuclear cells showed a similar distribution of DEC-205 staining on the leukocytes. DEC-205-specific semiquantitative immunoprecipitation/ western blot and quantitative reverse transcriptase-PCR analysis established that these leukocyte populations expressed DEC-205 protein and the cognate mRNA. Thus, human DEC-205 is expressed on more leukocyte populations than that were previously assumed based on mouse DEC-205 tissue localization studies. The broader DEC-205 tissue expression in man is relevant to clinical DC targeting strategies and DEC-205 functional studies. © 2006 Oxford University Press.