title: Interleukin-7 inhibits pre-T-cell differentiation induced by the pre-T-cell receptor signal and the effect is mimicked by hGM-CSF in hGM-CSF receptor transgenic mice.
abstract: We have previously reported that human granulocyte-macrophage colony-stimulating factor (hGM-CSF) causes a stage-specific inhibition of T-cell receptor (TCR) alphabeta cell development in the thymus of transgenic mice constitutively expressing the hGM-CSF receptor. Since it has been reported that the addition of interleukin-7 (IL-7) to fetal thymic organ culture (FTOC) has similar effects, we compared the effects of IL-7 and hGM-CSF on TCR(alphabeta) cell development in hGM-CSF receptor transgenic mice. We reconstituted fetal lobes with sorted pre-T, or post pre-T CD4(-)CD8(-) precursor cells. The addition of either IL-7 or hGM-CSF to these cultures suppressed further differentiation of pre-T cells but not post pre-T cells. At the same time, the cell number was increased, suggesting that pre-T-cell proliferation is stimulated by these cytokines. Furthermore, the differentiation of recombination-activating gene-1 (RAG-1)-deficient pre-T cells in response to anti-CD3 antibody stimulation was suppressed by either IL-7 or hGM-CSF, suggesting that these cytokines inhibit the pre-T-cell receptor (pre-TCR) signal. This inhibition is unexpected because the pre-TCR signal and the IL-7 signal have previously been considered to be co-operative. Recent analysis of the downstream events of IL-7 receptor and GM-CSF receptor revealed that they share common signal transduction molecules. Our results show that IL-7 is able to promote pre-T cell proliferation and to suppress differentiation induced by the pre-TCR signal. GM-CSF can mimic these biological activities of IL-7 when the pre-T cells express GM-CSF receptors. Our data suggest that both timing and level of activation of the IL-7 signalling pathway must be precisely regulated to facilitate the differentiation of thymocytes.
authors.affiliation: Department of Molecular and Developmental Biology, The Institute of Medical Science, The University of Tokyo, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Yasuda
authors.forename: Azusa
authors.initials: A
authors.lastname: Kaneko
authors.forename: Ichiko
authors.initials: I
authors.lastname: Nishijima
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Miyatake
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Arai
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000276:immunology; D002455:Cell Division / Q000276:immunology; D002470:Cell Survival / Q000276:immunology; D002478:Cells, Cultured; D016654:Genes, RAG-1 / Q000276:immunology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000276:immunology*; D006801:Humans; D015851:Interleukin-7 / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008822:Mice, Transgenic; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology
chemical_list: D015851:Interleukin-7; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor