T-cell memory: the connection between function, phenotype and migration pathways.

Immunological memory is a fundamental feature of vertebrate immune systems, providing enhanced protection against previously encountered antigens. The established view has been that immunological memory results from clonal expansion and long-term survival of specialized memory cells. Recently, the nature of memory T cells has come under closer scrutiny because of the ability to distinguish naive and memory T cells phenotypically, particularly in humans. In this article, Charles Mackay discusses three features of memory T cells that help to explain the nature and function of these cells: the increased expression of adhesion and activation molecules on memory T cells, their potent functional status and their specific pathways of recirculation.