Expression of CD103 identifies human regulatory T-cell subsets

Area of Science:

• Immunology
• Cell Biology

Background:

• Identifying human regulatory T cells (nTreg) is challenging due to the lack of specific surface markers.
• CD25, a common marker for nTregs, is also present on activated effector T cells, complicating analysis.

Purpose of the Study:

• To investigate if CD4+ T cells expressing CD103 function as suppressor cells, irrespective of CD25 coexpression.
• To determine the utility of CD103 as a specific marker for human nTreg cells.

Main Methods:

• Comparison of suppressive activity and FoxP3 mRNA levels in tonsillar CD103+ CD25- and CD103- CD25high cells.
• Induction of CD103 on in vitro-stimulated CD4+ T cells and subsequent comparison of CD103+ and CD103- fractions.
• Analysis of CD103+ nTreg cell frequency in neonatal versus adult T cells.

Main Results:

• Tonsillar CD4+ CD103+ CD25- T cells exhibited suppressive activity comparable to CD103- CD25high cells, with similar FoxP3 mRNA levels.
• In vitro-generated CD103+ T cells suppressed T-cell activation and showed higher FoxP3 mRNA than CD103- CD25+ cells.
• Neonatal alloreactive cells had more CD103+ nTregs and became hyporesponsive, unlike adult counterparts.

Conclusions:

• CD103 and CD25 coexpression defines three subsets of human CD4+ nTreg cells.
• CD103 serves as a reliable marker for identifying nTreg cells, independent of CD25 expression.
• Increased CD103+ suppressor cells in cord blood may explain its clinical efficacy in transplantation.