Cholesterol-rich endosomal and lysosomal membranes of antigen-presenting cells

Cholesterol-rich endosomal and lysosomal membranes in antigen-presenting cells (APCs), such as dendritic cells and macrophages, serve as critical platforms for the processing and loading of antigens onto MHC molecules. These specialized membrane microdomains, often referred to as lipid rafts, are characterized by high concentrations of cholesterol and sphingolipids, which organize signaling complexes and proteases required for immune surveillance (Source: Nature Reviews Immunology, 2015). In the context of vaccine development, these membranes are targeted by adjuvants like QS-21 that induce regulated membrane destabilization, allowing antigens to escape into the cytosol for MHC class I cross-presentation to CD8+ T cells (Source: Journal of Immunology, 2011). Additionally, lysosomotropic agents like hydroxychloroquine accumulate within these compartments, raising the internal pH and inhibiting the processing of self-antigens, which is a key therapeutic mechanism in treating systemic lupus erythematosus and rheumatoid arthritis (Source: Lancet, 2017). While not a single molecular entity, these membranes represent a functional therapeutic target for modulating the intensity and direction of the adaptive immune response.

Other names

Late endosomal/lysosomal membranesMIIC (MHC class II compartment)Cholesterol-rich membrane microdomainsLipid rafts in endolysosomes

Drugs or adjuvants interact with these membranes to either alter the pH (e.g., chloroquine), disrupt the membrane integrity to facilitate endosomal escape of antigens into the cytosol for cross-presentation (e.g., saponins), or modulate the activity of membrane-bound proteins involved in immune signaling.