Production of antibodies of identical idiotype but diverse immunoglobulin classes by cells derived from a single stimulated B cell

The availability of anti phosphocholine antibody of the TEPC 15 idiotype from the clonal progeny of a single precursor cell, stimulated in vitro, permitted the demonstration of monoclonal antibodies with as many as three immunoglobulin classes with identical variable regions. This demonstration was dependent on sensitive radioimmunoassays which showed a one to one relation between the total anti phosphocholine antibody produced by a clone and the sum of anti phosphocholine antibody of the different classes as well as the amount of antibody of the TEPC 15 idiotype. The class distribution was confirmed by isoelectric focusing identification of IgM, IgA, and IgGl antibodies of the TEPC 15 idiotype produced by single clones which showed characteristic pI values for each immunoglobulin class. Thus, within the generative phase of a single antibody producing cell clone, various heavy chain constant regions can be linked to the same variable region, and single precursor cells have the capacity to generate progeny expressing at least three distinct immunoglobulin classes.