Preliminary functional analysis of human epidermal T cells

Area of Science:

• Immunology
• Dermatology
• Cell Biology

Background:

• The precise function of human epidermal T cells (ETC) remains largely unknown.
• Dermal T cells (DTC) and ETCs are distinct populations within human skin.
• Understanding their interactions with keratinocytes is crucial for skin immunity.

Purpose of the Study:

• To investigate the functional differences between ETCs and DTCs.
• To explore the interaction of ETCs and DTCs with keratinocytes.
• To elucidate the mechanisms underlying ETC homing and retention in the epidermis.

Main Methods:

• Culturing of DTC, ETC, and keratinocytes from human skin.
• Expansion of T cell lines in interleukin-2 supplemented medium.
• Transfection of keratinocytes with HPV16 E6/E7 to create an immortalized line (HEK001).
• Assessment of lymphocyte migration and adhesion using calcein fluorimetric assays.
• Analysis of ICAM-1 expression on keratinocytes and T cells.
• Inhibition studies using anti-ICAM-1 antibodies.

Main Results:

• ETCs exhibited significantly higher migration (3-4 times) and adhesion (2-4 times) towards HEK001 compared to DTCs.
• A greater proportion of ETCs expressed cutaneous lymphocyte-associated antigen (26% vs 1% for DTCs).
• Keratinocyte ICAM-1 expression was upregulated upon stimulation and co-culture with T cells, mediating adhesion.

Conclusions:

• Human epidermal T cells (ETC) and dermal T cells (DTC) are functionally distinct populations.
• ETC migration and adhesion to keratinocytes are mediated, in part, by ICAM-1.
• Epidermotropism and selective retention are likely key mechanisms for ETC development and maintenance in skin.