Functional microtubules are required for antigen processing by macrophages and dendritic cells.
Antigen-presenting cells readily phagocytose antigens and channel them through various membrane-bound organelles within the cell. In previous studies, we demonstrated that macrophages concentrated and localized particulate antigens to the trans-Golgi prior to displaying the MHC-class I-antigenic peptides on the cell surface. In this study, we evaluated the importance of cytoskeletal elements in the intracellular trafficking of soluble and liposome-encapsulated ovalbumin in murine bone marrow-derived macrophages and human dendritic cells. F-actin, as identified by staining with fluorescein phalloidin, was observed at the point of contact between soluble or liposomal antigen and the cell membrane, suggesting that a rearrangement of the cytoskeleton occurs to facilitate the uptake of the antigens. Cells were incubated with colchicine, a microtubule depolymerizing agent, or paclitaxel, a microtubule polymerizing agent, before the addition of Texas Red-labeled ovalbumin or liposome-encapsulated Texas Red-labeled ovalbumin. Colchicine disrupted the trans-Golgi, whereas the trans-Golgi complexes were intact in paclitaxel treated cells. In either paclitaxel or colchicine-treated macrophages, internalized liposomal ovalbumin was not concentrated in the area of the trans-Golgi as determined by staining with fluorescent ceramide. In contrast, soluble ovalbumin was concentrated in the region of the trans-Golgi in 15% of the dendritic cells treated with paclitaxel, whereas 6% of the dendritic cells were able to concentrate liposomal antigen. In colchicine-treated dendritic cells, both soluble and liposomal antigens were internalized but did not localize to the area of the trans-Golgi. These data suggest that trafficking of soluble and liposome-encapsulated ovalbumin requires a functional microtubule-dependent translocation system.
Peachman
Kristina K
KK
Department of Membrane Biochemistry, Division of Biochemistry, Walter Reed Army Institute of Research, 503 Robert Grant Road, Silver Spring, MD 20910-7500, USA. kristina.peachman@na.amedd.army.mil
Rao
Mangala
M
Palmer
Dupeh R
DR
Zidanic
Michael
M
Sun
Wellington
W
Alving
Carl R
CR
Rothwell
Stephen W
SW
D000818:Animals; D017951:Antigen Presentation; D000938:Antigen-Presenting Cells / Q000378:metabolism; D000941:Antigens / Q000378:metabolism; D020126:Brefeldin A / Q000494:pharmacology; D003713:Dendritic Cells / Q000276:immunology* / Q000648:ultrastructure; D005260:Female; D006801:Humans; D008081:Liposomes; D008264:Macrophages / Q000276:immunology* / Q000648:ultrastructure; D051379:Mice; D008870:Microtubules / Q000502:physiology*; D010047:Ovalbumin / Q000008:administration & dosage; D010587:Phagocytosis; D021381:Protein Transport; D021601:trans-Golgi Network / Q000378:metabolism
D000941:Antigens; D008081:Liposomes; D020126:Brefeldin A; D010047:Ovalbumin