Induction of germ-line and mature C epsilon transcripts in human B cells stimulated with rIL-4 and EBV

J Immunol. 1990 Nov 15;145(10):3468-73.

Abstract

EBV and rIL-4 induce T cell-independent IgE production by normal human B cells. We demonstrate here that EBV and IL-4 induced the synthesis of IgE by surface IgE-negative B cell precursors isolated by cell sorting. This result suggests that the induction of IgE by EBV and IL-4 results not merely from the expansion of a precommitted surface IgE-positive B cell population but more likely from IL-4-directed switching to IgE. At the molecular level, IL-4 and EBV induced the appearance of 2.0- and of 1.8-kilobase (kb) RNA bands, both of which hybridized with an 0.88-kb HinfI fragment spanning part of the C epsilon 1 exon and the entire C epsilon 2 exon. The 1.8-kb band but not the 2.0-kb band also hybridized with a cloned genomic 0.7-kb SmaI fragment located approximately 2 kb upstream of C epsilon. Thus, EBV and IL-4 induced germline (1.8-kb) as well as mature (2.0-kb) C epsilon transcripts. IL-4 by itself induced germ-line C epsilon transcripts but not mature C epsilon transcripts in purified normal B cells. IL-4 failed to induce IgE synthesis in established EBV B cell lines and failed to induce 2.0-kb mature C epsilon transcripts but induced 1.8-kb germ-line C epsilon transcripts. These data show that IL-4 is sufficient for the induction of C epsilon germ-line transcription. In contrast, the transcription of mature epsilon mRNA requires an additional activating signal, provided by infection with EBV. Established EBV transformation results in a dissociation between germ-line C epsilon transcription and the ability to undergo IgE switching in response to IL-4.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antigens, Viral / analysis
  • B-Lymphocytes / immunology*
  • B-Lymphocytes / physiology
  • Epstein-Barr Virus Nuclear Antigens
  • Exons
  • Hematopoietic Stem Cells / immunology
  • Herpesvirus 4, Human / immunology*
  • Humans
  • Immunoglobulin E / biosynthesis*
  • Immunoglobulin E / genetics
  • Interleukin-4 / pharmacology*
  • Recombinant Proteins / pharmacology
  • Transcription, Genetic*

Substances

  • Antigens, Viral
  • Epstein-Barr Virus Nuclear Antigens
  • Recombinant Proteins
  • Interleukin-4
  • Immunoglobulin E