Novel innate PLZF⁺ αβ T cells

The transcription factor PLZF is required for the development of several innate-like populations of thymus-derived T cells. In the Journal of Immunology, two studies by Berg and colleagues identify and characterize a previously unknown PLZF⁺ population of TCRαβ⁺ T cells that arise in mice deficient in the TEC kinase Itk, which regulates TCR signaling. This T cell population, which differs from invariant natural killer T cells, MAIT cells and γδ T cells, has a diverse TCRα repertoire and does not require either β₂-microglobulin or major histocompatibility complex class II molecules for thymic development. The thymic development of these cells does require interactions between the SLAM family of adhesion factors and the adaptor SAP. However, CD4⁺ PLZF⁺ Itk^−/− thymocytes and their CD8⁺ counterparts seem to have different requirements for development. These cells 'preferentially' home to the spleen and gut, where their numbers are influenced by the microbiome. Thus, Itk activity seems to regulate the formation of a distinct subset of innate T cells.

J. Immunol. 193, 673–687 & 688–699 (2014)