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Characterisation of colony forming cells in the human thymus: Evidence for a suppressor mechanism


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Dalloul AH, Mossalayi MD, Bertho JM, Mouterde G, Debre P.
Experimental Hematology Volume 17, Issue 7, 1989, Pages 774-778

Type de document > *Article de revue

Mots clés > radioprotection, interleukine, thymus

Unité de recherche > IRSN/DRPH/SRBE/LTCRA

Auteurs > BERTHO Jean-Marc

Date de publication > 01/07/1989

Résumé

Activation pathways for thymic cell growth remain partially unknown. Thymocytes generally show low growth responses when cultured in the presence of mitogens, especially when T-cell colony formation by these cells is assayed. In the present work we studied the T-cell colony-forming ability of thymic subsets under phytohemagglutinin (PHA) and/or recombinant interleukin 2 (rIL2) stimulation. Our results confirm the low number of T-cell colonies obtained from human thymus as compared to bone marrow and peripheral blood sources. In contrast, significant colony numbers were observed when thymocytes were depleted of CD8+ cells. This increase was due to the suppression exerted by CD8+ cells on both CD4+- and CD4-, CD8--derived colony precursors. This inhibitory mechanism is dose-dependent and cannot be replaced by media conditioned by CD8+ cells. Limiting dilution analysis corroborates agar assays and points to the existence of T-cell colony-forming cells within the double-negative (CD4-, CD8+) thymi subset.