V(H) sequence of a human anti-Sm autoantibody. Evidence that autoantibodies can be unmutated copies of germline genes

I. Sanz, H. Dang, M. Takei, N. Talal, J. D. Capra

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Abstract

The utilization of germline genes for the synthesis of autoantibodies has been suspected for many years based on the presence of cross-reactive idiotypes among patients as well as in some healthy first-degree relatives of patients with several autoimmune diseases including SLE. One such system of idiotypes involves anti-Sm antibodies, which are highly specific for SLE. To definitively establish the utilization of germline genes in the Sm system, we produced human-human B cell hybridomas from a patient with SLE who had circulating anti-Sm antibodies. One stable hybridoma designated 4B4 secretes an IgM-κ mAb that binds Sm and shares idiotypic determinants with other anti-Sm antibodies. A second anti-Sm antibody (3C3), isolated from the same patient was also studied. Oligo(dT) priming was used to produce cDNA corresponding to full length IgM. Sequence analysis revealed that the V(H) gene segment (1-96) of 4B4 is identical to a V(H) sequence previously detected in a fetal liver cDNA library by Schroeder and his co-workers as well as a germline V(H) recently described by Berman and his associates. The identity of a lupus mAb and sequences derived from unrelated individuals provides strong evidence that this autoantibody is a direct copy of a germline gene.

Original languageEnglish (US)
Pages (from-to)883-887
Number of pages5
JournalJournal of Immunology
Volume142
Issue number3
Publication statusPublished - Jan 1 1989

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ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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