Table 2 Summary of some characteristics of the T regulatory cells

1. Definition

Cells with regulatory function that produce IL-10 and TGF-β and play a critical role in the control the immune response and the generation and maintenance of tolerance.

2. Properties

• heterogeneous group of lymphocytes

• exist in very low numbers

• respond poorly to stimulation through TCR

• unique and diverse mechanisms of action

• none common specific phenotypic marker

3. Some subtypes by phenotype

• CD4⁺CD25⁺

• CD4⁺CD45RB⁺

• CD8⁺

• TCRγδ⁺

• NT/NKT cells – e.g. Vα24-JαQ

• CTLA4⁺

4. Subtypes by cytokine profile

• Th3 cells: differentiate from naive CD4⁺ or CD8⁺ cells under the influence of TGF-β, produce TGF-β > IL-10, varying IL-4

• Tr1 cells: differentiate from naive CD4⁺ or CD8⁺ cells under the influence of IL-10, produce IL-10 > TGF-β, no IL-4