In vitro systems for the study of T cell development: fetal thymus organ culture and OP9-DL1 cell coculture.

Most T cell development occurs within the thymus and includes a series of selection processes that are, in large part, still poorly understood. Studies of T cell development have been greatly advanced by the description of multiple phenotypic subsets of T cells and their maturational relationships. This unit describes a system for observing and modulating T cell development in vitro via the culture of entire mouse fetal thymic lobes. Methods are included for the isolation of fetal thymi and culture to allow for normal T cell development on either transwell plates or Gelfoam sponges. A method for depleting hematopoietic cells from thymic lobes using 2'-deoxyguanosine and subsequent reconstitution with precursor cells is also described. This protocol is valuable for the study of tolerance and T cell selection. A support protocol describing methods of altering and monitoring T cell development are outlined. In addition, methods for culturing fetal thymic lobes under high oxygen submersion conditions and for the preparation of reaggregate thymus organ cultures are provided. Finally, a simple and practical method that allows for the thymus-independent generation of T cells from defined sources of stem/progenitor cells by OP9-DL1 coculture is described.