Immunoglobulin V region variants in hybridoma cells. I. Isolation of a variant with altered idiotypic and antigen binding specificity.

The hybridoma cell line B1-8.delta 1 expresses an IgD antibody with specificity for the hapten 4-hydroxy-3-nitro-phenylacetyl (NP). Two monoclonal antibodies, each recognizing an idiotypic determinant (idiotope) in the variable region of antibody B1-8, and fluorescence-activated cell sorting were used for the isolation of spontaneous somatic cell variants whose antibody product lacks the expression of one of the two idiotopes. The variant cells carry a mutation which is expressed in the variable region of the antibody heavy chains and which reduces the affinity of the antibody for hapten greater than 100-fold. Idiotope loss variants of the selected phenotype are present in the B1-8.delta 1 cell population at low frequency.