Naive T cell

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Naive T cell refers to a T cell that has differentiated in bone marrow, and successfully undergone the positive and negative processes of central selection in the thymus. A naive T cell is considered mature, but is distinguished from activated T cells or memory T cells, as it is thought to not have yet encountered cognate antigen in the periphery.

Naive T cells are commonly characterized by the surface expression of L-selectin (CD62L); the absence of the activation markers CD25, CD44 or CD69; and the absence of memory markers, such as the edited CD45 isoforms. In the naive state, T cells are thought to be quiescent and non-dividing, requiring the common-gamma chain cytokines IL7 and IL15 for homeostatic survival.

Naive T cells are able to respond to novel pathogens that the immune system has not yet encountered. Recognition by a naive T cell clone of its cognate antigen results in the initiation of an acquired immune response. In the ensuing response, the T cell acquires an activated phenotype (CD25⁺CD44⁺CD62L^lowCD69⁺), and may further differentiate into a memory T cell.

[edit] See also

• Immune system
• Memory T cells