Use of 'single shot' intrasplenic immunization for production of monoclonal antibodies specific for human IgM.

We report here the use of 'single shot' intrasplenic injection of human IgM for immunization of mice to obtain splenocytes for use in the production of hybridomas secreting antibodies against human IgM. Fusion was performed 3 days after intrasplenic injection of 20 micrograms of myeloma IgM. IgM-specific antibodies were found in 12% of the fusion wells; only 1 well contained antibodies which cross-reacted with other immunoglobulin classes. Two monoclonal antibodies (McAbs) have been fully characterized as specific for different epitopes on Fc mu. These antibodies can be used to detect IgM on the surface of human B cells by immunofluorescence and in solution by solid-phase radiobinding assay or single radial immunodiffusion. Both McAbs can also detect IgM fragments by immunoblotting from non-reducing SDS-polyacrylamide gels.