Expression of recombination-activating genes and terminal deoxynucleotidyl transferase and secondary rearrangement of immunoglobulin κ light chains in rheumatoid arthritis synovial tissue

Zhixin Zhang, Xing Wu, Brent H. Limbaugh, S. Louis Bridges

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

Objective. Lymphocytic infiltrates in rheumatoid arthritis (RA) synovium often resemble lymphoid follicles and contain clonally related Ig transcripts, suggesting in situ antigen-dependent B cell selection. Recent reports have shown expression of recombination-activating genes (RAGs) and concurrent secondary rearrangement of Ig genes in normal peripheral lymphoid organs (receptor revision). We sought to determine if RAG-mediated receptor revision of Ig κ light chains occurs in B cells within the RA synovium. Because we previously reported enhanced N-region addition at VL-JL joins in clonally expanded light-chain transcripts from RA synovium, we also sought expression of terminal deoxynucleotidyl transferase (TdT), which is normally expressed only in B cell precursors or immature B cells. Methods. Reverse transcription-polymerase chain reaction (PCR) was used to detect RAG and TdT transcripts from unselected and B cell-enriched synovial and peripheral blood mononuclear cells obtained from 12 RA patients. Activity of RAG protein was sought using ligation-mediated PCR to detect recombination intermediates, and immunohistochemistry was performed to identify RAG+ cells within synovia. Results. We found evidence of RAG-mediated secondary Ig κ light chain rearrangements in about one-third of RA synovia. TdT expression was found in several samples, but did not correlate with RAG expression. Conclusion. RAG-mediated secondary Ig rearrangements of κ light chains may contribute to the local production of antibodies to autoantigens (e.g., rheumatoid factor) or exogenous antigens, or it may represent a failed attempt at immune tolerance. TdT expression suggests the presence of immature B cells in RA synovia. These findings have important implications for the local generation of antibodies in RA and other chronic inflammatory diseases.

Original languageEnglish (US)
Pages (from-to)2275-2284
Number of pages10
JournalArthritis and rheumatism
Volume44
Issue number10
DOIs
StatePublished - 2001
Externally publishedYes

ASJC Scopus subject areas

  • Immunology and Allergy
  • Rheumatology
  • Immunology
  • Pharmacology (medical)

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