Figure 2.

Indirect cytotoxicity of human killer DC subsets. Antigen-loaded killer DCs have the ability to activate antigen-specific cytotoxic T cells that in turn can lyse target cells. Whether killer DCs also have the ability to cross-present antigens obtained from killed target cells and thereafter cross-prime cytotoxic T cells is unclear. Furthermore, human pDCs produce large amounts of type I IFNs upon stimulation and, next to a direct cytotoxic effect, can exert indirect cytotoxic effects by: (i) activating NK cells; (ii) enhancing antigen cross-presentation and cross-priming of T cells; and (iii) generating of IFNα-induced killer MoDCs/mDCs. Abbreviations: CPG, CpG oligodeoxynucleotides; DC, dendritic cell; Flu, influenza; FSME, früh sommer meningo-encephalitis; HIV-1, human immunodeficiency virus 1; HTLV, human T lymphotropic virus; IFN, interferon; NK, natural killer; TBEV, tick-borne encephalitis virus.