Followinig the development of T cells in the thymus, they enter the blood stream and recirculate between the blood and peripheral lymphatic tissues. Mature recirculating T cells that have not yet encountered their specific antigen are known as naive T cells. Mature T cell not yet exposed to antigen with the phenotype CCR7-positive, CD45RA-positive, and CD127-positive. This cell type is also described as being CD25-negative, CD62L-high and CD44-low.