Cross-linking of surface immunoglobulins and endocytosis of antigen are not sufficient to suppress antibody production of two hybridoma cell lines.
The two cell lines Lev 1-3 and AS3, which secrete monoclonal anti-levan antibody and express surface membrane immunoglobulins that are capable of binding the levan, were cultured for 24 h or 48 h with levan of various molecular weights (5 x 10(4), 2 x 10(5) or 2 x 10(7) daltons). The production of antibody was measured by a plaque-forming cell assay for AS3 cells and by biosynthetic labelling for Lev 1-3 cells. Surface immunoglobulins were detected by a rosette-forming cell assay. By using immunoenzymatic procedures, we observed that levan of 5 x 10(4) and 2 x 10(5) daltons was intensely endocytosed by the cells and localized mainly in the cellular center, whereas levan of 2 x 10(7) daltons remained mostly associated with the plasma membrane and formed surface aggregates. After transfer of cells in levan-free medium, it was shown that internalized levan could persist several days inside the cells without being degraded. Viability, growth, antibody synthesis and secretion were not modified in cells cultured with levan, whatever the molecular weight of the antigen used. Our results show that cross-linking of surface immunoglobulins by multivalent antigen or endocytosis of antigen do not appear to be sufficient to induce a suppression of antibody production or membrane immunoglobulin expression.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis; D002455:Cell Division; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology; D004705:Endocytosis; D005630:Fructans / Q000276:immunology*; D006825:Hybridomas / Q000276:immunology*; D007136:Immunoglobulins / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D011134:Polysaccharides / Q000276:immunology*; D012397:Rosette Formation
D000911:Antibodies, Monoclonal; D005630:Fructans; D007136:Immunoglobulins; D011134:Polysaccharides