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Updated: Aug 13, 2026

Generation of Human CD40-activated B cells
13:27

Generation of Human CD40-activated B cells

Published on: October 17, 2009

Human dendritic cells activate T lymphocytes via a CD40: CD40 ligand-dependent pathway

A D McLellan1, R V Sorg, L A Williams

  • 1Haematology/Immunology Research Group, Christchurch Hospital and Christchurch School of Medicine, New Zealand.

European Journal of Immunology
|June 1, 1996
PubMed

Insights

The CD40:CD40 ligand (CD40L) interaction is crucial for T lymphocyte activation. Dendritic cells (DCs) require differentiation to express CD40, influencing T cell proliferation through CD80/CD86-dependent and independent pathways.

Area of Science:

  • Immunology
  • Cell Biology

Background:

  • The CD40:CD40 ligand (CD40L) interaction is vital for immune responses, mediating T lymphocyte help for B cells and monocytes, and acting as a co-stimulus for T lymphocyte activation.
  • Understanding the regulation of CD40 expression on human dendritic cells (DCs) and its functional role in T lymphocyte stimulation is critical for immune modulation.

Purpose of the Study:

  • To investigate the regulation of CD40 expression on human dendritic cells (DCs).
  • To determine the functional relevance of CD40:CD40L interaction in DC-mediated T lymphocyte stimulation.

Main Methods:

  • Flow cytometry was used to assess CD40 expression on isolated blood DCs and after culture with various cytokines.
  • Functional assays, including allogeneic mixed leukocyte reactions, were performed using CD40 immunoglobulin (CD40Ig) fusion protein and CD40L monoclonal antibodies to block CD40:CD40L interactions.
  • T lymphocyte proliferation and IL-2 secretion were measured.

Main Results:

  • Directly isolated blood DCs expressed minimal CD40, which was significantly upregulated by culture and cytokines (IL-1α, IL-1β, IL-3, TNF-α, GM-CSF).
  • CD40L expression was not detected on DCs. Blocking CD40:CD40L interaction with CD40Ig or CD40L antibodies reduced T lymphocyte proliferation.
  • Cross-linking CD40 on DCs enhanced CD80/CD86 upregulation but inhibited T lymphocyte proliferation, suggesting complex regulatory roles. Simultaneous blockade with CTLA-4Ig showed minimal additive effects.

Conclusions:

  • Both CD80/CD86-dependent and -independent pathways are involved in DC-T lymphocyte co-stimulation via the CD40:CD40L interaction.
  • Most blood DCs require differentiation or activation to express essential co-stimulatory molecules like CD40 for effective T lymphocyte stimulation.

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