Monoclonal antibodies to an immunoglobulin allotype marker G1m(f).

The properties of a group of mouse monoclonal antibodies (McAbs) specific for the human G1m(f) allotype marker on immunoglobulin G are described. The specificity of all 5 McAbs was anti-Gm(f) in haemagglutination assays detecting the G1m(f) determinant on 6 ng of purified G1m(f) paraproteins. A high dilution (greater than or equal to 1/10(4)) could be used for the majority of McAbs in this assay. In Elisa the G1m(f) marker could be detected in homozygote G1m(f+z-) sera at a serum dilution of greater than or equal to 1/10(4). In Elisa assays the G1m(f) specificity was lost when IgG was bound directly to polystyrene but was restored when IgG was bound via anti-human IgG to the polystyrene plate. A possible conformational change in IgG to account for this loss of specificity is discussed. It is expected that these McAbs with their high titre and increased sensitivity over conventional Gm antisera will allow more detailed analysis of the Gm marker system.