Activation of human dendritic cells through CD40 cross-linking.

Abstract

Sllmm~'yDendritic cells, the professional antigen-presenting cells (APC) involved in T cell priming, express CD40, a molecule which triggering plays a key role in B cell growth and differentiation as well as monocyte activation. Herein we demonstrate that dendritic Langerhans cells (D-I.c) generated by culturing cord blood CD34 + progenitor cens with granulocyte/macrophage colony-stimulating and tumor necrosis factor oe (TNF-c~) express functional CD40 at a density higher than that found on B cells. Culturing D-IX on CD40-ligand (CD40L) transfected L cells allowed D-IX survival as 50 • 15% of seeded cells were recovered after 4 d while only 5% survived over control L cells. CD40 activation induced important morphological changes with a reduction of cytoplasmic content and a remarkable increase of dendrite development as well as an altered phenotype. In particular, CD40 triggering induced maintenance of high levds of major histocompatibility complex class II antigens and upregulation of accessory molecules such as CD58, CD80 (B7-1) and CD86 (B7-2). CD40 engagement also seems to turn on D-IX maturation as illustrated by upregulation of CD25, a molecule usually expressed on interdigitating dendritic cells of secondary lymphoid organs. Finally, CD40 activated D-IX secreted a limited set of cytokines (TNF-c~, IL-8, and macrophage inflammatory protein 1,', [MIP-loc]) whereas a similar activation induced dutriated monocytes to secrete IL-lot, IL-1/5, IL-6, IL-8, IL-10, TNF-~x, and MIP-lo~. As D-Ix activated T cells upregulated CD40L, it is likely that CD40 activation olD-ix observed herein with a fibroblast cell line stably expressing CD40L, mimics physiological interactiom between dendritic cells and T cells.T he CD40 antigen (1, for review) was identified by monodonal antibodies reacting with carcinomas and B cells (2) and showing costimulatory effects for B lymphocytes (3). It is a 50-kD glycoprotein which bdongs to the TNF receptor superfamily (4). Cross-linking of CD40, in conjunction with IL-4, was found to induce B cells to undergo long-term growth, as well as isotype switching, whereas addition of IL-10 results in B cell differentiation as well as isotype switch (5-8). The use of a CD40-~ fusion protein allowed the isolation of a cDNA encoding for a CD40 ligand (CD40L) 1, a new member of the TNF superfamily mainly expressed on activated T cells (9). Interaction between CD40 and CD40L has now been shown in vitro to be essential during T cell-de. pendent B cell activation (10,11). In vivo studies in mice have demonstrated that an antibody to CD40L can inhibit primary and secondary antibody production and establish- Functional CD40 molecules were found to be expressed on cells other than mature B cells. In particular, upon CD40 cross-llnklng, human progenitor B lymphocytes express CD23 and proliferate in response to . Thymic epithelial cells secrete GM-CSF in response to CD40 engagement (19). Finally, monocytes express high leveh of CD40 after eq, osure to IFN-% IL-3, and GM-CSF and CD40 cross-llnklng induces cyto...

CD40L expressed from the canarypox vector, ALVAC, can boost immunogenicity of HIV-1 canarypox vaccine in mice and enhance the in vitro expansion of viral specific CD8+ T cell memory responses from HIV-1-infected and HIV-1-uninfected individuals

“…Consistent with previous results using exogenous CD40L trimer [26,37,38], we found CD40L expressed from canarypox vector could activate and mature human MDDCs to a greater extent than that of the parental control virus or a clinically used HIV-1 canarypox vaccine, vCP205. ALVAC virus has previously been shown to activate and mature DCs via ingestion of apoptotic DCs and TNF-α secretion induced by ALVAC infection [39,59,60].…”

“…A recombinant canarypox vector expressing a membrane form of human CD40L, vA3131-2, was constructed and expression of human CD40L in infected cells was verified by flow cytometry and Western blot (data not shown). Previous studies show that CD40L could activate and mature human monocyte derived dendritic cells, which then can expand immune responses [26,37,38]. Therefore, we first studied the effect of CD40L expressing from the canarypox vector on human immature monocyte derived dendritic cells (iMDDCs).…”

CD40 expression on human pancreatic duct cells: role in nuclear factor-kappa B activation and production of pro-inflammatory cytokines

“…A soluble form of CD40L is released from activated platelets or shed from stimulated lymphocytes [21,22,23,24]. CD40-CD154 interactions were shown to play a pivotal role in different T-cell-mediated inflammatory disorders [20,21,25,26,27] and disruption of CD40-CD40L interactions proved to be sufficient to prevent the development and progression of several autoimmune diseases [28,29] as well as allograft rejection [21,26].…”

Modulating Co-Stimulation

“…There is also evidence that engagement of CD40 and CD154 leads to upregulation of B7 expression on APCs. 45,46 The mechanisms of EAE inhibition by blockade of the CD28-B7 co-stimulatory pathway by the fusion protein CTLA4Ig or anti-B7 monoclonal antibodies (mAbs) have been investigated by several laboratories. 12,14,26,47,48 Blockade of CD28-B7 or CD40-CD154 pathways was successful in preventing or ameliorating ongoing disease in numerous other autoimmune disease models.…”