E-cadherin-mediated adhesion involving Langerhans cell-like dendritic cells expanded from murine fetal skin

Langerhans cells (LC), the epidermal contingent of the dendritic cell (DC) lineage, migrate from skin to regional lymph nodes to initiate primary immune responses against Ag encountered in skin. Because E-cadherin mediates LC-keratinocyte adhesion, E-cadherin expression and/or function must be modulated during LC migration. To facilitate studies of LC/DC cadherin biology, we defined culture conditions that allowed expansion of LC-like cells from fetal murine skin. Fetal skin-derived dendritic cells (FSDDC) were propagated from C57BL/6 day 16 fetal skin in GM-CSF- and CSF-1-supplemented media. After 14 days, aggregates of E-cadherin+ FSDDC (FSDDC-A) that resembled freshly-obtained LC with regard to phenotype and function were isolated. Nonadherent FSDDC (FSDDC-NA) with dendritic morphology, surface phenotype identical to that of interdigitating DC and potent allostimulatory capacity were released from FSDDC-A with continued incubation. A survey of cytokine mRNAs expressed by FSDDC revealed that FSDDC-A expressed predominantly TNF-alpha, TGF-beta1, and MIF mRNA. In contrast, FSDDC-NA exhibited de novo expression of IL-1beta, IL-12 (p40), increased levels of TNF-alpha and decreased MIF mRNA. Neutralizing anti-E-cadherin mAb dissociated FSDDC-A into single cells, whereas functionally inactive anti-E-cadherin mAb and mAb reactive with other adhesion molecules did not, demonstrating that adhesion within FSDDC-A was E-cadherin-mediated. FSDDC-A also preferentially adhered to E-cadherin-transfected fibroblasts. Spontaneous dissociation of FSDDC-A was accompanied by a reduction in cell surface E-cadherin expression. The availability of large numbers of cells with characteristics of LC in situ that spontaneously mature into interdigitating DC will permit detailed studies of LC/DC cadherin biology and LC/DC differentiation.