Endosomal membrane in antigen-presenting cells

The endosomal membrane in antigen-presenting cells (APCs) is a specialized subcellular structure that plays a pivotal role in the immune system by facilitating the processing and presentation of antigens. It serves as the primary site for the MHC class II loading pathway, where internalized proteins are proteolytically cleaved into peptides for display to T cells (Roche & Furuta, 2015, Nature Reviews Immunology). Additionally, the endosomal membrane houses critical pattern recognition receptors, such as Toll-like receptors (TLR3, TLR7, TLR8, and TLR9), which sense pathogen-associated molecular patterns like nucleic acids (Kawai & Akira, 2011, Immunity). Although it is a cellular compartment rather than a single molecular target, its unique environment is exploited by various pharmacological agents. For example, antimalarial drugs like hydroxychloroquine concentrate in endosomes to raise the luminal pH, which inhibits the activation of endosomal TLRs and is used to treat autoimmune diseases (Kuznik et al., 2011, Journal of Immunology). Furthermore, synthetic ligands for endosomal receptors are being developed as vaccine adjuvants and cancer immunotherapies to stimulate robust immune responses.

Other names

Endosomal compartmentEndocytic membraneAntigen-processing compartmentPhagosomal membrane

Modulation of endosomal pH or activation/inhibition of endosomal receptors such as Toll-like receptors (TLRs).