Cultured murine dermal cells can function like thymic nurse cells

Area of Science:

• Immunology
• Dermatology
• Cell Biology

Background:

• Fibroblast-like stromal cells are crucial for immune cell development and function in lymphoid organs.
• The skin's microenvironment and its resident stromal cells' roles in cutaneous immunity are not fully understood.

Purpose of the Study:

• To establish and characterize novel fibroblast-like stromal cell lines from mouse skin.
• To investigate the potential of these cells to support T-cell interactions and cytokine production.
• To explore their functional similarity to thymic nurse cells.

Main Methods:

• Establishment of dermal fibroblast-like stromal cell lines (DFB-1 and clone 12E2) from BALB/c mouse ear epidermis.
• Morphological and phenotypic characterization using phase-contrast microscopy and marker analysis.
• Assessment of T-cell interaction via "pseudo-emperiporesis" with T-cell clones and hybridomas.
• Quantification of interleukin-7 (IL-7) secretion using bioassays and antibody inhibition.
• Detection of IL-7 mRNA expression via RT-PCR and Southern blot analysis.

Main Results:

• DFB-1 and 12E2 cells exhibited fibroblast/myofibroblast characteristics, lacking tonofilaments, desmosomes, and bone marrow/macrophage markers.
• These cells demonstrated "pseudo-emperiporesis" by allowing T-cells to migrate beneath their cytoplasmic projections.
• Secretion and mRNA expression of interleukin-7 (IL-7) were confirmed in these stromal cells.
• The findings suggest these skin stromal cells function similarly to thymic nurse cells.

Conclusions:

• Unique fibroblast-like stromal cells (DFB-1) exist in mouse skin, likely in the upper dermis.
• These cells possess nurse cell-like properties, supporting T-cell interactions and producing IL-7.
• These findings indicate a significant role for skin stromal cells in cutaneous immunophysiology.