Section 6
Chapter 5,731

Interleukin 2 pathway is autonomously activated in human t11 positive 3 negative 4 negative 6 negative 8 negative thymocytes

D.L.H.ra A.; Toribio, M.L.; Marcos, M.A.R.; Marquez, C.; Martinez, A.C.

European Journal of Immunology 17(5): 683-688


ISSN/ISBN: 0014-2980
Accession: 005730651

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Mitogenic membrane ligands have been shown to activate interleukin 2 (IL 2) production only in mature T cells, IL 2 constitutive secretion having not yet been demonstrated. Here we have isolated a population of T11+3-4-6-8- human thymocytes and CD7+/T11-3-4-6-8- prothymocytes which produce and consume IL 2 upon phytohemagglutinin triggering. Interestingly, their proliferation in the absence of any exogenous stimulating agent was related to an autonomous use of the IL 2 system (IL 2 secretion and binding to its specific receptor, whose constitutive, functional expression in human early thymocytes was recently shown). The internal activation of this system before T cell receptor acquisition stresses the relevance of the understanding of the alternative activation pathway(s) in T cell development. These findings, together with the demonstration of IL-2-promoted differentiation of human early thymocytes into mature T cells, suggest that IL2 may also be a growth and differentiation factor acting specifically early in T cell development.

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