Generation of T cells from adult human hematopoietic stem cells and progenitors in a fetal thymic organ culture system:: stimulation by tumor necrosis factor-α

To investigate the T-lymphopoietic capacity of human adult bone marrow (ABM) hematopoietic progenitor cells, CD34+ Lin-, CD34+CD38+, and CD34++CD38- cells were cultured in a severe combined immunodeficient (SCID) mouse fetal thymic organ culture (FTOC), Direct seeding of these progenitors resulted in a moderate to severe cell loss, particularly for the CD34+ +CD38- cell fraction, and T cells could only be generated from the CD34+Lin- fraction. Preincubation for 36 hours with interleukin-3 (IL-3) and stem cell factor (SCF) led to an improved cell survival and proliferation, although T-ceIl development was seen only in the CD34+Lin- fraction. Addition of tumor necrosis factor (TNF)-alpha to IL-3 + SCF-supplemented preincubation medium resulted in optimal cell survival, cell proliferation, and T-cell generation of all 3 cell fractions. The TNF-alpha effect resulted in an up-regulation of CD127 tie, the IL-7 receptor alpha-chain) in a small subset of the CD34+ cells. No evidence could be generated to support the possibility that TNF-alpha inhibits a cell population that suppresses T-cell differentiation. A quantitatively different T-cell generation potency was still seen between the 3 subpopulations: CD34+Lin- (100% success rate) > CD34+CD38+ (66%) > CD34++CCD38- (25%). These data contrast with our previous findings using fetal liver and cord blood progenitors, which readily differentiate into T-lymphocytes in FTOC, even without prestimulation with cytokines, Our results demonstrate that adult CD34++CD38- cells, known to contain hematopoietic stem cells, can differentiate into T-lymphocytes and that a significant difference exists in T-lymphopoietic activity of stem cells derived from ontogenetically different sources. (Blood. 2000; 95:2806-2812) (C) 2000 by The American Society of Hematology.