TLR ligands differentially affect uptake and presentation of cellular antigens.

Dendritic cells (DCs) have the unique ability to efficiently present T-cell epitopes from exogenous antigens on MHC class I molecules, a process called cross-presentation. In our study we demonstrate that stimulation of monocyte-derived DCs with Toll-like receptor (TLR) ligands differentially affects the uptake and cross-presentation of cellular antigens. Activation of DCs with TLR3 or TLR4 but not with TLR2 or TLR7/8 ligands inhibited phagocytosis of apoptotic tumor cells and resulted in a reduced cross-presentation of pp65-derived T-cell epitopes on MHC class I molecules upon engulfment of cytomegalovirus (CMV)-infected fibroblasts.