An immunoglobulin light chain from a lupus-prone mouse induces autoantibodies in normal mice

Autoantibodies against the 70-kD U1 RNP nucleoprotein autoantigen and DNA were elicited in normal BALB/c mice with a purified Ig light chain. This light chain, derived from a lupus-prone MRL-lpr/lpr mouse, has two distinctive properties: it contains an idiotypic marker recognized by a monoclonal MRL-lpr/lpr anti-snRNP autoantibody, and the amino acid sequence of its third hypervariable region (CDR3) is homologous to a sequence in an antigenic region of the 70-kD U1 RNP polypeptide. The results demonstrate that an Ig idiotype that mimics an autoantigen can induce autoimmunization.