Abstract
T helper precursor cells have been well characterized in human bone marrow. These cells require exposure to thymic epithelium or its products for their acquisition of functional activity. We now describe a population of marrow resident T suppressor precursor cells which require exposure to IL2 for their functional maturation. This population is completely distinct from helper cell precursors. It expresses T8 and TAC (IL2 receptor) determinants and acquires E receptors, T3 determinants and suppressive activity towards immunoglobulin secreting B lymphoid cells after as little as 4 hours of incubation in the presence of cell line derived or recombinant IL2. Helper precursors, in contrast, are T4+/T8−/TAC− and on density gradients they are separated as large buoyant cells from the small, dense suppressor precursors. In 2 patients with SCID, IL2 dependent T precursor cells appeared only late following thymic epithelial transplantation, after small numbers of T lymphocytes had appeared in marrow and circulation. We propose a model where pathways of extrathymic T cell differentiation are preceded by and dependent on the initiation of intrathymic T cell development. With about 1011 IL2 dependent T suppressor precursor cells present in an adult bone marrow, these cells may play an important role in immune homeostasis.
This work was supported by PSI (Ontario), the MRC and NCI of Canada.
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Dosch, HM., Hibi, T. & Mills, G. 969 CHARACTERIZATION OF IL2-DEPENDENT MARROW T PRECURSOR CELLS. Pediatr Res 19, 272 (1985). https://doi.org/10.1203/00006450-198504000-00999
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DOI: https://doi.org/10.1203/00006450-198504000-00999