Reactivity, flexibility, kinetics and exhaustion in myeloid and plasmacytoid dendritic cells (DCs). The figure summarizes the properties of immature myeloid and plasmacytoid DCs. Indicated are the most relevant Toll-like receptors (TLR) and chemokine receptors, and the response to various maturation stimuli. DC1 and DC2 refer to the capacity of the cells to induce Th1 and Th2 responses, respectively. CD40L, CD40 ligand; LPS, lipopolysaccharide; PGE2, prostaglandin E2.