In psoriasis pathogenesis, the IL-23/Th17 axis is central. Which cell type produces IL-23 (p19/p40 heterodimer) to drive Th17 differentiation and acts as the primary initiator?
- A Myeloid dendritic cells (mDC) activated by innate signals ✓
- B CD4+ Th1 cells producing IFN-gamma
- C Plasmacytoid dendritic cells (pDC) producing type I interferons
- D Keratinocytes producing IL-17 directly
Correct answer: A. Myeloid dendritic cells (mDC) activated by innate signals
Explanation
In psoriasis, environmental triggers (trauma, infection, drugs) activate innate signals (LL-37 antimicrobial peptide complexes with self-DNA/RNA activating TLRs on pDCs and mDCs). Myeloid dendritic cells (mDC) are the primary source of IL-23 (and IL-12), driving differentiation of naïve T-cells into Th17 cells. Th17 cells produce IL-17A, IL-17F, and IL-22, which act on keratinocytes to cause hyperproliferation. pDCs produce type I IFNs (early innate phase). Keratinocytes do not produce IL-17.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.