Recruitment of γ/δ T-Cells and Other T-Cell Subsets to Sites of Inflammation

Abstract

Effective immune responses against pathogens require the migration of diverse sets of lymphoid cells into tissues that occurs both under homeostatic conditions and during inflammation associated with infection. Most mature naive α/β T-cells recirculate from the blood into secondary lymphoid organs, such as lymph nodes and Peyer’s patches on a continual basis. They reenter the blood via the lymphatics. This process of recirculation provides the naive T-cell access to the organs of the body that collect antigen from epithelial surfaces, somatic tissues, and blood. Once T-cells respond to antigen, become activated, proliferate, and eventually develop into memory cells, they exhibit different trafficking behaviors, preferentially homing to extra-lymphoid sites of inflammation, such as inflamed skin or arthritic joints. In some instances, inflammation leads to the tissue-specific accumulation of distinct memory α/β T-cell subsets. Other specialized T-cells, such as γ/δ T-cells, exhibit trafficking patterns similar to memory α/β T-cells (preference for extralymphoid sites of inflammation). γ/δ T-cells can also exhibit constitutive homing to noninflamed, epithelial cell—associated tissues (reviewed in refs. 1–12).