Origin, differentiation, and repertoire selection of CD3+CD4-CD8- thymocytes bearing either alpha beta or gamma delta T cell receptors.

摘要: It has been widely accepted that CD3+CD4-CD8- T cells expressing TCR-alpha beta or TCR-gamma delta (found in the thymus as well periphery) represent lineages distinct from either CD4+CD8- and CD4-CD8+ single-positive beta. However, origin, differentiation pathway, TCR-repertoire selection of remain controversial. We demonstrate thymocytes can be separated into three subsets based on their expression heat-stable Ag (HSA) CD44. Our results further suggest following: 1) HSA+ subset represents a pre-selection population, although HSA- is postselection subset; 2) high incidence V 8.2 usage among result positive selection, rather than predetermined event at precursor cell level; 3) maturation proceeds along following pathway: HSA+CD44(-)-->HSA-CD44(-)-->HSA-CD44+. Both +CD4-CD8- show similar processes; 4) CD3+CD4-CD8-cells directly differentiate CD25+CD3-CD4-CD8- which include for both CD4+CD8-/CD4-CD8+ lineages. Taken together, these stage thymocyte branching point