Circulating human plasmacytoid dendritic cells are highly sensitive to corticosteroid administration

Area of Science:

• Immunology
• Endocrinology
• Hematology

Background:

• Plasmacytoid dendritic cells (pDCs) are key interferon-producing cells implicated in systemic lupus erythematosus (SLE) pathogenesis.
• Previous SLE studies noted pDC abnormalities, often in patients receiving corticosteroids.
• The impact of corticosteroids on pDCs in healthy individuals remained unclear.

Purpose of the Study:

• To investigate the effects of prednisone administration on pDC numbers and function in healthy adults.
• To assess the reversibility of steroid-induced changes in pDCs after drug withdrawal.

Main Methods:

• Four healthy volunteers received prednisone (15-30 mg/day) for 4 days.
• pDC counts and their capacity for IFN-alpha production were measured during and after prednisone treatment.
• Peripheral blood leukocyte populations were analyzed.

Main Results:

• Prednisone significantly reduced both pDC counts (P=0.02) and IFN-alpha production (P=0.004).
• The reduction in IFN-alpha was due to decreased cell numbers and lower IFN-alpha output per cell.
• Granulocyte counts showed opposite changes, while other leukocytes were minimally affected.
• pDC levels and function rapidly recovered post-treatment.

Conclusions:

• Corticosteroids, specifically prednisone, suppress pDC numbers and IFN-alpha production in healthy adults.
• These effects are reversible, indicating a direct impact of steroids on pDC homeostasis.
• Findings provide crucial insights into how steroid therapy might influence immune responses in conditions like SLE.