Confocal laser scanning microscopic analysis of macrophages co-cultured with DQ-OVA-liposome conjugates MHC class I of macrophages were stained with red fluoresceinlabeled anti-mouse H-2D d mAb (Fig. 1A : left column), and MHC class II of macrophages were labeled with DM-DsRed ( Fig. 1A : right column) as described in Materials and Methods. DQ-OVA, which exhibits green fluorescein upon proteolytic degradation, was coupled to liposomes consisting of unsaturated (oleoyl) or saturated (stearoyl) fatty acid, and added to the culture of macrophages. After incubation for 2 hr, the recovered macrophages were analyzed using confocal laser scanning microscopy. The results shown in Fig. 1 demonstrate that DQ-OVA coupled to oleoyl liposomes was processed at both MHC class I and class II compartments, while most of the DQ-OVA coupled to stearoyl liposomes was processed at the MHC class II compartment.