JAG2 induces an LCH-like phenotype in vitro. Monocytes were cultured with the indicated cytokines in the presence of JAG2 or control transfected CD45⁻ MS5 feeder cells for 5 days. Cells were collected and stained for CD45 to allow separation of monocyte-derived cells from feeder cells, along with Abs against the LCH-associated markers CD1a and Langerin. (A) Induction of CD1a shown as the percentage of CD1a⁺ cells among the CD45⁺ population. (B) Detection of TGF-β1 mRNA in frozen biopsy material taken from LCH lesions and from healthy human skin and bone. TGF-β1 expression is normalized to B2M. (C) CD1a⁺ cells were further analyzed for the coexpression of Langerin and E-cadherin. Histogram plots show Langerin and E-cadherin expression of CD1a⁺CD45⁺ cells shown in panel A. (C) DCs generated in the presence of GM-CSF, TGFβ1, and JAG2. Langerin staining (red) reveals the presence of numerous rod-shaped Langerin⁺ organelles in the cytoplasm indicative of the presence of Birbeck granules. Cell borders were determined by phase contrast (cyan).