Molecular analysis of the autoantibody response in peptide-induced autoimmunity

Immunization of nonautoimmune BALB/c mice with multimeric DWEYSWVLSN, a pep tide mimotope of DNA, induces anti-DNA and other lupus-associated Abs, To f urther investigate the pathogenesis of the autoantibody response induced by peptide immunization, rye generated hybridomas from peptide-immunized mice that bound peptide, dsDNA, cardiolipin, Sm/ribonucleoprotein (RNP), or som e combination of these Ags, Analysis of 24 IgM Abs led to the identificatio n of three groups of Abs: I) Abs reactive with peptide alone, 2) anti-pepti de Abs cross-reactive with one or more autoantigens, and 3) autoantibodies that do not. bind to peptide. The gene families and particular V-H-V-L comb inations used in those hybridomas binding DNA were similar to those used in the anti-DNA response in spontaneous murine lupus, Another similarity to t he spontaneous anti-DNA response was the generation of arginines in the com plementarity-determining region-3 of DNA-binding hybridomas, interestingly, one Ab had the V-H-V-L combination present in the original R4A anti-DNA Ab used to select the DWEYSVWLSN peptide from a phage display library. Many o f the heavy and light chains displayed evidence of somatic mutation, sugges ting that they were made by Ag-activated B cells, Analysis of the Ab repert oire in peptide-induced autoimmunity may provide insights into the generati on of anti-DNA Abu following exposure to foreign Ag, Furthermore, the recov ery of an Ab with the heavy and light chain combination of the kb originall y used to isolate the immunizing peptide confirms the utility of phage disp lay peptide libraries in generating true molecular mimics.