Molecular cloning of the primary IgH repertoire: a quantitative analysis of VH gene usage in adult mice.

The generation of the primary antibody repertoire requires the somatic rearrangement of germline gene segments. It is not known, however, whether all functional V and J gene segments have an equal probability of contributing to this initial set of antibody specificities. To address this issue, we have examined the relative utilization of VH and JH gene segments of the mouse. We have constructed VH cDNA phage libraries from C mu transcripts obtained from polyclonally activated spleen cells of the BALB/c and C57BL/6 strains. We show that probes specific for either one, two or three functional VH gene segments hybridize to cDNAs at frequencies directly proportional to the number of functional germline VH genes detected by each probe. In contrast, the representation of 10 VH gene families within each library indicates that certain families are under-represented relative to their estimated germline gene number. These families must either have extraordinary proportions of nonfunctional genes or are influenced by as yet unidentified regulatory mechanisms or constraints on rearrangement.