Expression of the CD40 ligand in t lymphocytes and induction of IgE isotype switching

Ramsay Fuleihan*, Deborah Ahem, Raif S. Geha

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


CD40 ligand (CD40L) delivers a contact-dcpendent signal to B cells which, in the presence of interleukin (IL)-4, drives immunoglobulin isotype switching to IgE. CD40L expression in T cells is transient, requires activation of protein kinase C and a rise in intracellular calcium concentration ([Ca2), and is inhibited by cyclosporin A (CsA). CsA also inhibited T-cell-dependent IL-4-driven IgE synthesis. We have found that expression of CD40L is developmentally regulated. Expression ofCD40L was restricted to mature single-positive thymocytes which, in the presence of IL-4, were capable of inducing B cells to undergo IgE isotype switching. CD40L expression was severely decreased in cord blood lymphocytes and was associated with a severely decreased ability to undergo T-celldependent IgE isotype switching. Caremark and from NMC Homecare. RF is the recipient of a Clinical Investigator Award from the NIAID, K08 AI-01091.

Original languageEnglish (US)
Pages (from-to)43-44
Number of pages2
JournalInternational archives of allergy and immunology
Issue number1-3
StatePublished - 1995


  • B cells
  • CD40 ligand
  • Cord blood
  • Cyclosporin A
  • IgE
  • Immunoglobulin isotype switching
  • Interleukin-4
  • Newborn
  • T cells
  • Thymocytes

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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