title: The induction of macrophage spreading by factor B of the properdin system.
abstract: Unstimulated mouse peritoneal macrophages attached to a glass substratum responded to activated human factor B (Bb) of the properdin system but not to native factor B with rapid spreading and a concomitant increase in their apparent surface area. Excellent correlation of the distribution of Bb protein and cell-spreading activity was found upon purification of Bb by ion-exchange and molecular seive chromatography and alkaline polyacrylamide gel electrophoresis. 1.6 microgram of purified Bb was sufficient to induce spreading in 50% of 5 x 10(4) glass attached macrophages within 1-2 h at 37 degrees C. Treatment of Bb with di-isopropyl-fluorophosphate indicated that the intact catalytic site of the serine-proteinase Bb was required for the initiation of macrophage spreading. The involvement of factor B in the induction of rapid cell spreading could also be indirectly demonstrated in an autologous system in which F(ab')2 fragments of an antiserum to mouse B prevented mouse macrophages from spreading in response to complement-activated mouse serum. These experiments suggest a role for factor B and the alternative pathway of complement fixation in the localization of mononuclear phagocytes to areas of inflammation.
mesh_terms: D000818:Animals; D001202:Ascitic Fluid / Q000276:immunology; D001665:Binding Sites; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D011415:Complement Factor B / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004792:Enzyme Precursors / Q000276:immunology*; D006801:Humans; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008970:Molecular Weight; D010446:Peptide Fragments / Q000494:pharmacology; D013045:Species Specificity
chemical_list: D004792:Enzyme Precursors; D010446:Peptide Fragments; D011415:Complement Factor B