LONG-TERM CULTURE OF TRIPLE-NEGATIVE THYMOCYTES

The role of the thymic microenvironment in regulating events that occu r subsequent to the acquisition of CD4, CD8, and the TCR, such as posi tive and negative selection, has been studied extensively, However, co mparatively less is known about how thymic stromal cells regulate grow th and differentiation within the CD4(-)CD8(-)TCR(-) triple negative ( TN) cell compartment, Long-term culture systems have played a pivotal role in the understanding of microenvironmental regulation of myelopoi esis and B lymphopoiesis, but establishment of comparable cultures for T lineage cells has proved challenging, This report describes a cultu re system in which a thymic stromal cell line preferentially supports the long-term growth of TN thymocytes, In addition to demonstrating th at TN cells have a considerable proliferative potential, the results p rovide insights into the effects of IL-7 on the growth and/or survival of TN cells and its role in regulating TCR gene rearrangements, The a bility of the cultured TN cells to mature into CD4- and/or CD8-express ing thymocytes, some of which express TCR-alpha beta, suggests that th e system will be valuable for the identification of microenvironmental stimuli that regulate the maturation of TN cells.