Conventional and unconventional T cells

Abstract

T lymphocytes that express an αβ T cell receptor (TCR), as well as a co-receptor CD4 or CD8, are present in the peripheral blood, lymph nodes, and tissues (such as the skin), and are considered conventional T cells. Unconventional T cells include those lymphocytes that express aδTCR, and may commonly reside in an epithelial environment such as the skin, gastrointestinal tract, or genitourinary tract. Their role is to recognize infections and cancer cells, and regulate inflammatory responses that arise in these tissues. Another subset of unconventional T cells is that of the invariant natural killer T (NKT) cell, which has phenotypic and functional capacities of a conventional T cell, as well as features of natural killer cells (cytolytic activity). NKT cells recognize glycolipids when presented in the context of CD1d, and play a role in allergy, autoimmunity, and host defense against cancer and infections. © 2008 Springer London.