The CMRF58 antibody recognizes a subset of CD123hidendritic cells in allergen‐challenged mucosa

CD123hiCD11c−dendritic cells (CD123hiDC) are a distinct subset of human DC present in bone marrow, blood, lymphoid organs, and peripheral tissues. Pathogen stimulation, cytokine, or CD40 ligation induces CD123hiDC maturation, involving a shift from their innate immune to cognate antigen‐presenting functions. In this study, we revealed that blood CD123hiDC in the presence of cytokine (granulocyte macrophage‐colony stimulating factor and interleukin‐3) undergo progressive, step‐wise maturation through an “early” stage, delineated by expression of the antigen detected by the new monoclonal antibody CMRF58 (CD123hiCMRF58+CD40−CD86−CD83−) to the “late” stage with costimulatory antigen expression (CD123hiCMRF58+CD40+CD86+CD83+/−). In this early stage, cytokine‐maintained CD123hiDC do not display changes in their morphology, no longer produce interferon‐α (IFN‐α) in response to bacteria, and develop the capacity to induce proliferation and polarization of allogeneic T cells. CD123hiCMRF58+DC, phenotypically similar to in vitro cytokine‐maintained CD123hiDC, were not detected in tonsil but are present in allergen‐challenged nasal mucosa of allergic individuals. Thus, CD123hiDC in certain tissue environments such as allergen‐challenged nasal mucosa share a common CD123hiCMRF58+phenotype with in vitro cytokine‐maintained blood CD123hiDC characterized by lack of IFN‐α production.