Increased expression of IL-12p70 and IL-23 by multiple dendritic cell and macrophage subsets in plaque psoriasis

J Dermatol Sci. 2009 May;54(2):99-105. doi: 10.1016/j.jdermsci.2009.01.003. Epub 2009 Mar 4.


Background: Psoriasis is a chronic immune-mediated skin disease, in which interleukins 12 and 23 have been postulated to play a critical role. However, the cellular source of these cytokines in psoriatic lesions are still poorly defined and their relative contribution in inducing skin inflammation has been discussed controversially.

Objectives: To investigate immunoreactivity of the bioactive forms of IL-12 and IL-23 in plaque psoriasis and to characterize the dendritic cell (DC) and macrophage subsets responsible for the production of these cytokines.

Methods: Immunohistochemistry was performed on normal skin (n=11) as well as non-lesional (n=11) and lesional (n=11) skin of patients with plaque psoriasis using monoclonal antibodies targeting the bioactive forms of IL-12 (IL-12p70) and IL-23 (IL-23p19/p40) on serial cryostat sections using the alkaline phosphatase-antialkaline phosphatase. Co-localization of IL-12 and IL-23 with different dendritic cells and macrophage cell markers (CD1a, CD11c, CD14, CD32, CD68, CD163, CD208/DC-LAMP) was performed using double immunofluorescence staining.

Results: Immunoreactivity for IL-12 and IL-23 was significantly enhanced in lesional psoriatic skin as compared to non-lesional and normal skin. No difference was observed between IL-12 and IL-23 immunoreactivity in any skin types. Both IL-12 and IL-23 immunoreactivity was readily detected mainly in CD11c+, CD14+, CD32+, CD68+ and some CD163+, DC-LAMP+ cells. IL-12 and occasionally IL-23 were also found in some CD1a+ dendritic cells. In addition, an enhanced expression mainly of IL-23 was observed in keratinocytes.

Conclusions: Bioactive forms of IL-12 and IL-23 are highly expressed in various DC and macrophage subsets and their marked in situ production suggest that both cytokines have crucial pathogenic role in psoriasis.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Dendritic Cells / cytology
  • Dendritic Cells / immunology*
  • Female
  • Humans
  • Interleukin-12 / biosynthesis*
  • Interleukin-23 Subunit p19 / biosynthesis*
  • Keratinocytes / immunology
  • Macrophages / cytology
  • Macrophages / immunology*
  • Male
  • Middle Aged
  • Psoriasis / immunology*
  • Psoriasis / pathology
  • Skin / immunology*
  • Skin / pathology


  • Interleukin-23 Subunit p19
  • Interleukin-12