Hapten-specific B cell repertoire probed by hybridoma technology: selection and characterization of representative clonotypes from the antibody-forming cell pool.

In the course of this study, more than 3000 phthalate-specific antibody-forming cell hybrids were identified using the hybridoma technology. With the aid of a rapid screening assay and an extensive library of phthalate analogs, it was possible to assign selected hapten-specific clones to one of 11 distinct fine-specificity sets. This compartmentalization of the phthalate-specific hybridomas has made it possible to focus attention upon a single manageable portion of the phthalate-specific repertoire. Fourteen clones from a single fine-specificity set were selected for further immunochemical characterization. Five of these clones were found to secrete an antibody that was indistinguishable in isoelectric focusing. Affinity-purified, high-resolution anti-idiotype antibodies were prepared with specificity for the antibodies produced by one of these clones (i.e., 4C7). A major portion of the serologically defined private idiotype (4C7 IdI) was shown to be associated with the ligand-combining site. Our results indicate that the five clones that share a common spectrotype also express the 4C7 IdI. Two other independently derived clones from two distinct fusions also share this idiotype. The 4C7 IdI was also identified in affinity-purified anti-phthalate antibodies derived from a pool of phthalate-immune serum (conventional antibody) and from affinity-purified antibodies derived from a pool of serum from unimmunized BALB/c mice (natural antibody). The 4C7 IdI is thus considered to represent a repeating clonotype in the phthalate-specific repertoire of BALB/c mice, and will serve as one of several useful clonal markers that are being developed for studies of the mechanism regulating idiotype expression.