title: Evidence that agarose must be internalized to stimulate mouse macrophages in vitro.
abstract: Agarose stimulation of macrophages in vitro was studied. Under conditions where agarose was ingested, stimulation was detected during 24-48 h of incubation at a time when the agarose increasingly was concentrated in the perinuclear region. Removal of extracellular agarose after 24 h when endocytosis had reached a plateau did not reduce the stimulatory effect. Preincubation for 4 days with dextran sulphate in concentrations reported to inhibit phagosome-lysosome fusion potentiated strongly the stimulatory effect. In all situations in which agarose was not internalized--in teflon tubes where the cells remain in suspension, on glass cover slips with inhibitors (2-deoxy-D-glucose, cytochalasin B), or with large, noningestible Sepharose beads--no stimulation was recorded. The possibility is discussed that stimulation of macrophages by agarose may be related to complement activation in phagosomes.
mesh_terms: D000818:Animals; D003078:Colchicine / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D016264:Dextran Sulfate; D003911:Dextrans / Q000494:pharmacology; D004705:Endocytosis / Q000187:drug effects; D006801:Humans; D008262:Macrophage Activation / Q000187:drug effects; D051379:Mice; D008809:Mice, Inbred C3H; D008811:Mice, Inbred DBA; D011134:Polysaccharides / Q000502:physiology*; D012685:Sepharose / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*
chemical_list: D003911:Dextrans; D011134:Polysaccharides; D003571:Cytochalasin B; D012685:Sepharose; D016264:Dextran Sulfate; D003078:Colchicine