Expression of Iμ-Cγ hybrid germline transcripts subsequent to immunoglobulin heavy chain class switching

Suzanne C. Li, Paul B. Rothman, Jue Zhang, Christina Chan, David Hirsh, Frederick W. Alt

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


Germline CH transcripts initiate from a non-coding I exon and terminate downstream of the associated CH exons. Ig heavy chain class switch recombination from the VDJ - Cμ gene to particular downstream CH genes appears to be regulated by a process that involves mltogen and/or cytokine induction of germline CH transcripts from the downstream genes. We have examined the expression of germline Cμ transcripts (Iμ-Cμ transcripts) in splenic B cells and pre-B cell lines after cytokine and mltogen stimulation. In contrast to the expression of the germline transcripts from downstream CH genes, expression of germline Cμ transcripts was constitutive and unaffected by mltogen and cytokine treatment. After a primary switch recombination event, the germline Iμ promoter, which is now associated with a downstream CH gene, continues to be active-leading to the generation of a novel germline transcript consisting of the Iμ exon spliced to the CH exons of the switched CH gene. We discuss the potential role of the expression of hybrid Iμ-contalning transcripts in the class switch process. We also describe a novel and sensitive assay, based on the detection of the hybrid Iμ-contalnlng transcripts, that allows detection of class switch recombination events even in heterogeneous populations of cells.

Original languageEnglish (US)
Pages (from-to)491-497
Number of pages7
JournalInternational Immunology
Issue number4
StatePublished - Apr 1994
Externally publishedYes


  • Class switching
  • Heavy chain
  • Immunoglobulin

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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