Tissue-specific NK cell populations and their origin.

Tissue-specific NK cell subpopulations are found in adult gut, liver, and endometrium, as well as other sites in the body. Some differ phenotypically and functionally from pbNK cells, and their origin is disputed. In this review, we discuss tissue-specific NK cells and suggest that subpopulations differentiate in situ from tissue-resident hematopoietic progenitor cells. The understanding of the origins and maturation requirements of tissue-specific NK cells could lead to new classes of immunotherapy for organ-specific pathologies of infectious and malignant origin.