Immunoglobulin heavy chain class switch from IgM to IgG in a hybridoma.

A subclone of an IgM-producing hybridoma has been identified which has switched to producing an IgG1 antibody. The parent hybridoma, PC-140, produces an antibody which binds phosphorylcholine and reacts with monoclonal antibodies that recognize myelomas of the T-15 idiotype. The IgG1 antibody binds phosphorylcholine with the same affinity as the parental IgM and also reacts with the anti-T-15 monoclonal antibodies. While the IgM-producing parent hybridoma does not express detectable surface IgM, the IgG1-producing subclone produces both membrane and secreted IgG1.