ABSTRACT
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.
Subject(s)
Antibodies, Monoclonal/immunology , Hybridomas/drug effects , Hybridomas/immunology , Immunoglobulin Class Switching/drug effects , Mutagens/pharmacology , Aminacrine/analogs & derivatives , Aminacrine/pharmacology , Animals , Antibodies, Monoclonal/genetics , Genetic Variation , Immunoglobulin Class Switching/genetics , Mice , Mutagenesis , Nitrogen Mustard Compounds/pharmacologyABSTRACT
We have shown that one of the alleles in a hybridoma was nonproductive because the sequence in the N region of the heavy chain caused it to be out of frame and to terminate prematurely. This allele became productive, and the gamma 1 heavy chain that it encoded was secreted when an adenosine was inserted to produce an open reading frame. This event occurred at a very low frequency following mutagenesis of the cultured cells. This result suggests that similar sorts of events must occur in vivo when both productive and nonproductive alleles undergo frequent mutations and that new genes may be expressed in hybridomas as they are being subcloned.
