title: A role for microfilaments but not microtubules in processing soluble antigens.
abstract: Ag processing involves multiple intracellular membrane transport events required for delivery of Ag to degradative compartments in the endocytic pathway of antigen-presenting cells (APC) and transport of newly synthesized class II MHC proteins to compartments where peptide loading occurs. Movement and distribution of various subcellular vesicles have been shown to involve elements of the cytoskeletal network. We have examined the role of microtubules and microfilaments in Ag processing and presentation by B lymphoblastoid cells. Experiments with nocodazole or colchicine, drugs that disrupt the microtubule network, demonstrate that intact microtubules are not required for efficient processing of soluble Ag in these cells. Cytochalasins, which disrupt actin microfilaments, are observed to partially inhibit processing of soluble Ag. Inhibition is reversible and dependent on both the dose of drug and length of exposure. Control experiments demonstrate that the effect does not result from drug toxicity or decreased Ag uptake. Treatment of APC with cytochalasin B does not block delivery of internalized protein to dense lysosomes. However, the ability of the cells to catabolize internalized protein is partially inhibited. Our results suggest that microfilament-dependent, but not microtubule-dependent, vesicular transport may be required for efficient Ag processing in B lymphoblastoid cells.
authors.affiliation: Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Soreng
authors.forename: D A
authors.initials: DA
authors.lastname: Weber
authors.forename: H
authors.initials: H
authors.lastname: Joshi
authors.forename: J C
authors.initials: JC
authors.lastname: Moore
authors.forename: P E
authors.initials: PE
authors.lastname: Jensen
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects / Q000502:physiology*; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D001692:Biological Transport / Q000276:immunology; D002460:Cell Line; D003571:Cytochalasin B / Q000494:pharmacology; D006825:Hybridomas; D008247:Lysosomes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008870:Microtubules / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism
chemical_list: D003571:Cytochalasin B