T cell receptor gamma delta expression of Thy-1+ dendritic epidermal cells--an update

Thy-1+ dendritic epidermal cells (Thy-1+DEC) are present in the murine epidermis. They are morphologically dendritic and express Thy-1, CD3 and asialoGM1, but not CD4 or CD8. T cell receptor (TCR) of Thy-1+DEC is TCR gamma delta. Allison et al and Tonegawa et al recently found that TCR of Thy-1+DEC is V gamma 5 J gamma C gamma -V delta 1D2J2C delta and has no junctional diversity. This TCR gamma delta of Thy-1+DEC is identical to TCR expressed on the earliest fetal thymocytes. It is distinct from that of other epithelial associated lymphocytes or other thymocytes. The ligand of Thy-1+DEC is not known, although TCR gamma delta of adult type could recognize allogenic major histocompatibility complex(MHC) class I or class II and mycobacterium antigen, especially heat shock protein. The TCR of Thy-1+DEC may not be the homing receptor to epidermis. The further studies are needed to elucidate the ligands or functions of Thy-1+DEC.