title: Differentiation in Acanthamoeba castellanii is induced by specific monoclonal antibodies.
abstract: Monoclonal antibodies that bind a large molecular weight plasma membrane protein of Acanthamoeba castellanii cause the cells to differentiate. A different monoclonal antibody that binds specifically to the major plasma membrane protein has no effect upon cell division or differentiation. The induction of differentiation by the monoclonal antibodies requires a bivalent attachment, more than a single binding cycle of the antibody to the plasma membrane protein, does not require cell-cell contact, and appears to be mediated by an inhibition of pinocytosis. These results suggest one of two alternatives: either this free living amoeba possesses a cell surface receptor that serves to initiate the differentiation process when stimulated, or the specific plasma membrane antigen for the differentiation-inducing monoclonal antibodies is an essential component of the pinocytotic mechanism. While it seems more likely on the basis of available evidence that we are observing the biological effects of a cell surface receptor, either of the two alternative circumstances open up investigative areas of large significance.
mesh_terms: D000656:Amoeba / Q000254:growth & development* / Q000276:immunology / Q000502:physiology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001665:Binding Sites; D002455:Cell Division; D008565:Membrane Proteins / Q000276:immunology; D010873:Pinocytosis
chemical_list: D000911:Antibodies, Monoclonal; D008565:Membrane Proteins