Soluble antigens are presented to dendritic cells (DCs) in some cases by receptor mediated endocytosis or fluid-phase endocytosis. Burgdorf et al. (2008) suggest that there are two different endocytic compartments for antigen processing: one dedicated to MHC class I (early endosomes) and the other one for MHC class II presentation (lysosomes). Sorting of cargo into these different compartments occurs at the plasma membrane and is likely to depend on the type of endocytic receptor the cargo is interacting with (Burgdorf et al. 2008, Zhuang et al. 2006). The mannose receptor (MR) is the best studied receptor that targets soluble antigens to early endosomes but not to lysosomes (Burgdorf et al. 2006). Antigens taken up by the MR are targeted towards a mildly acidic stable early endosomal compartment for exclusive presentation on MHC I molecules (Burgdorf et al. 2008).