Clonal analysis of a human antibody response. III. Nucleotide sequences of monoclonal IgM, IgG, and IgA to rabies virus reveal restricted V kappa gene utilization, junctional V kappa J kappa and V lambda J lambda diversity, and somatic hypermutation.

In previous work, we generated four IgM, five IgG1, and one IgA1 mAbs to rabies virus using B cells from four subjects vaccinated with inactivated rabies virus, a thymus-dependent (TD) mosaic Ag, and sequenced the mAb V(H)DJ(H) genes. Here, we have cloned the V kappa J kappa and V lambda J lambda genes to complete the primary structure of the Ag-binding site of these mAbs. While the anti-rabies virus mAb selection of VA genes (2e.2.2 twice, DPL11, and DPL23) reflected the representation of the V lambda genes in the human haploid genome (stochastic utilization), that of V kappa genes (O2/O12 twice, O8/O18, A3/A19, A27, and L2) did not (p = 0.0018) (nonstochastic utilization). Furthermore, the selection of both V kappa and V lambda genes by the anti-rabies virus mAbs vastly overlapped with that of 557 assorted V kappa J kappa rearrangements, that of 253 V lambda J lambda rearrangements in lambda-type gammopathies, and that of other Abs to thymus-dependent Ags, including 23 anti-HIV mAbs and 51 rheumatoid factors, but differed from that of 43 Abs to Haemophilus influenzae type b polysaccharide, a prototypic thymus-independent (TI) Ag. The anti-rabies virus mAb V kappa J kappa and V lambda J lambda segments displayed variable numbers of somatic mutations, which, in mAb58 and the virus-neutralizing mAb57, entailed a significant concentration of amino acid replacements in the complementarity-determining regions (p = 0.0028 and p = 0.0023, respectively), suggesting a selection by Ag. This Ag-dependent somatic selection process was superimposed on a somatic diversification process that occurred at the stage of B cell receptor for Ag rearrangement, and that entailed V gene 3' truncation and N nucleotide additions to yield heterogeneous CDR3s.