Use of mutagens to increase rate of immunoglobulin isotype switching of hybridoma cells.

Isotype switching of hybridoma clones may be essential when the class of the antibody produced does not suit the task for which it was generated. In those instances immunoglobulin (Ig) switch variants can be isolated in vitro but the success of isolating these rare variants primarily depends on the frequency of switching of each individual hybridoma. Variations in the frequency are noted not only between hybridomas secreting different classes but also between fresh clones isolated from the same hybridoma. Immunoglobulin switch variants may be identified and isolated using the sib selection and the ELISA spot assay; however, when the frequency of switching is low, this may be extremely difficult and sometimes impossible. In the present article we demonstrate that ICR191 may increase the frequency of switching and that these Ig switch antibodies maintain the same antigen specificity and normal-sized heavy chain.