title: Granulocyte-macrophage colony-stimulating factor augmentation of T-cell receptor-dependent and T-cell receptor-independent thymocyte proliferation.
abstract: The effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) are not confined to cells of the myeloid lineage. GM-CSF has been shown to have effects on mature T cells and both mature and immature T-cell lines. We therefore examined the GM-CSF responsiveness of murine thymocytes to investigate whether GM-CSF also affected normal immature T lymphocytes. The studies presented here indicate that GM-CSF augments accessory cell (AC)-dependent T-cell receptor (TCR)-mediated proliferation of unseparated thymocyte populations. To identify the GM-CSF responsive cell type, thymic AC and T cells were examined for GM-CSF responsiveness. We found that GM-CSF augmentation of TCR-induced thymocyte proliferation appears to be mediated via augmentation of AC function, and not via direct effects on mature single-positive (SP) thymocytes. Enriched double-negative (DN) thymocytes were also tested for GM-CSF responsiveness. GM-CSF induced the proliferation of adult and fetal DN thymocytes in an AC-independent and TCR-independent single-cell assay. Thus, in contrast to the SP thymocytes, a DN thymocyte population was directly responsive to GM-CSF. GM-CSF therefore may play a direct role in the expansion of DN thymocytes and an indirect role in the expansion of SP thymocytes.
authors.affiliation: Department of Molecular Genetics and Biochemistry, University of Pittsburgh, PA 15213.
authors.forename: A M
authors.initials: AM
authors.lastname: Stewart-Akers
authors.forename: J S
authors.initials: JS
authors.lastname: Cairns
authors.forename: D J
authors.initials: DJ
authors.lastname: Tweardy
authors.forename: S A
authors.initials: SA
authors.lastname: McCarthy
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000187:drug effects; D005260:Female; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D015375:Receptors, Interleukin-2 / Q000032:analysis; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2; D016178:Granulocyte-Macrophage Colony-Stimulating Factor