Fig. 2.

Maturation steps of DCs and the different models for the origin of the functionally distinct DC subsets, DC1 and DC2. Functionally distinct DCs can originate from a single lineage, which has different activation states that are dependent entirely on the local environment signals (the functional plasticity model) or from completely separate developmental lineages where the signals effect lineage segregation earlier in the developmental pathway and the DCs precursors are already separated and functionally committed (the specialized lineage model). Although distinct in the immunological outcome by skewing Th1 and Th2 responses, both subsets become good antigen-presenting cells upon maturation and increase surface expression of co-stimulatory molecules (modified from [35]).