High level IL-12 production by murine dendritic cells: upregulation via MHC class II and CD40 molecules and downregulation by IL-4 and IL-10.

Abstract

SummaryWe have shown previously that dendritic cells (DC) produce IL-12 upon interaction with CD4+ T cells. Here we ask how this IL-12 production is induced and regulated. Quantitative PCR. and in situ hybridization for IL-12 p40 and an ELISA specific for the p70 heterodimer were used to determine IL-12 production. We demonstrate that ligation of either CD40 or MHC class II molecules independently trigger IL-12 production in DC, and that IL-12 production is downregulated by IL-4 and IL-10. The levels ofbioactive IL-12 that can be released by triggering with an anti-CD40 mAb or with a T cell hybridoma are high (range 260-4700 pg/ml from 1 • 106 DC in 72 h). The CD40-mediated pathway indicates that IL-12 production is induced in DC upon interaction with activated, CD40 ligand-expressing helper T cells, even in the absence of cognate antigen recognition. Side-by-side comparison oflL-12 production, and blocking experiments employing an anti-CD40 ligand n'LAb, suggest that the CD40-mediated pathway is quantitatively more significant than induction via the MHC class II molecule. The importance of the CD40/CD40 ligand interaction for IL-12 induction in DC likely contributes to the recent finding that mice lacking the CD40 ligand are impaired in mounting Thl type cell-mediated immune responses. IL-12, a 70-kD heterodimeric cytokine composed of co-.valentty linked p35 and p40 chains has emerged as a central cytokine in the immune response (1). IL-12 stimulates NK cells, mediates Thl development, and fosters CTL development. It can be produced by monocytes and macrophages in response to intracellular pathogens, bacteria (e.g., staphylococci) and bacterial products. Recent reports indicate that dendritic cells (DC) also release bioactive IL-12. One report described that anti-IL-12 blocks the capacity of murine DC to skew the response of naive transgenic T cells to the Thl phenotype (2), and another shows induction of IL-12 p40/p35 mRNA in bone-marrow derived murine DC upon uptake ofmicroparticle-absorbed protein antigen (3). Human epidermal Langerhans cells are also a source of IL-12 (4). We have recently used several criteria for demonstration of IL-12 p40 and p35 mRNA as well as IL-12 p40 and bioactive p70 proteins, to show that murine and human DC release IL-12 upon conventional stimuli such as staphylococcus aureus (5). We also found that DC produced bioactive IL-12 upon interaction with T cells without standard stir " ~-,~h as bacterial products. Here, we describe the regulation oflL-12 in DC.

Synergistic antitumor effect by coexpression of chemokine CCL21/SLC and costimulatory molecule LIGHT

“…40 CD40L also provides the primary stimulus for induction of IL-12, which is critically important for generation of CTL,41 by mature DCs. [42][43][44] In vitro, CCL21 has been reported to be a chemotactic factor for CD4 þ T cells. 36,45 Therefore, CCL21 and LIGHT may enhance the function of CD4 þ T cells without increasing the cell number or the infiltration of CD4 þ T cells into tumor may occur in earlier time after tumor inoculation.…”

CD40L‐expressing CD8 T cells prime CD8α+ DC for IL‐12p70 production

“…CD40-CD40L interaction is essential for CD8 T cellmediated IL-12p70 production CD40 stimulation is important for IL-12p70 production by DC [25,29,30]. To investigate whether CD40-CD40L interactions were involved in our system, we obtained DC from CD40 -/-mice for coculture with activated CD8 T cells and LPS (Fig.…”

“…Data are representative of at least three independent experiments and shown as mean AE SD. IFN-c and other CD8 T cell-derived soluble factors were insufficient to prime DC for IL-12p70, and that additional mechanisms mediated through cell-cell contact were necessary for CD8 T cell-mediated IL-12p70 production.CD40-CD40L interaction is essential for CD8 T cellmediated IL-12p70 production CD40 stimulation is important for IL-12p70 production by DC [25,29,30]. To investigate whether CD40-CD40L interactions were involved in our system, we obtained DC from CD40 -/-mice for coculture with activated CD8 T cells and LPS (Fig.…”

A TaqI polymorphism in the 3′UTR of the IL-12 p40 gene correlates with increased IL-12 secretion

“…1 Whereas the p35 chain is constitutively expressed in many cell types, expression of IL-12 p40, and therefore the p70 heterodimer, occurs mainly in dendritic cells, macrophages and monocytes after one of several stimuli. [2][3][4] IL-12 plays a key role in the modulation of the immune response by providing the stimulus for CD4+ T cells and NK cells to differentiate towards Th1, IFNg secreting cells, which in general is associated with cell-mediated immunity. In this capacity, IL-12 plays a key role in the defense against intracellular microorganisms.…”