title: Cytokine production by mature and immature CD4-CD8- T cells. Alpha beta-T cell receptor+ CD4-CD8- T cells produce IL-4.
abstract: This study follows our previous investigation describing the production of four cytokines (IL-2, IL-4, IFN-gamma, and TNF-alpha) by subsets of thymocytes defined by the expression of CD3, 4, 8, and 25. Here we investigate in greater detail subpopulations of CD4-CD8- double negative (DN) thymocytes. First we divided immature CD25-CD4-CD8-CD3- (CD25- triple negative) (TN) thymocytes into CD44+ and CD44- subsets. The CD44+ population includes very immature precursor T cells and produced high titers of IL-2, TNF-alpha, and IFN-gamma upon activation with calcium ionophore and phorbol ester. In contrast, the CD44- subset of CD25- TN thymocytes did not produce any of the cytokines studied under similar activation conditions. This observation indicates that the latter subset, which differentiates spontaneously in vitro into CD4+CD8+, already resembles CD4+CD8+ thymocytes (which do not produce any of the tested cytokines). We also subdivided the more mature CD3+ DN thymocytes into TCR-alpha beta- and TCR-gamma delta-bearing subsets. These cells produced cytokines upon activation with solid phase anti-CD3 mAb. gamma delta TCR+ DN thymocytes produced IL-2, IFN-gamma and TNF-alpha, whereas alpha beta TCR+ DN thymocytes produced IL-4, IFN-gamma, and TNF-alpha but not IL-2. We then studied alpha beta TCR+ DN T cells isolated from the spleen and found a similar cytokine production profile. Furthermore, splenic alpha beta TCR+ DN cells showed a TCR V beta gene expression profile reminiscent of alpha beta TCR+ DN thymocytes (predominant use of V beta 8.2). These observations suggest that at least some alpha beta TCR+ DN splenocytes are derived from alpha beta TCR+ DN thymocytes and also raises the possibility that these cells may play a role in the development of Th2 responses through their production of IL-4.
authors.affiliation: DNAX Research Institute, Palo Alto, CA 94304.
authors.forename: A
authors.initials: A
authors.lastname: Zlotnik
authors.forename: D I
authors.initials: DI
authors.lastname: Godfrey
authors.forename: M
authors.initials: M
authors.lastname: Fischer
authors.forename: T
authors.initials: T
authors.lastname: Suda
mesh_terms: D000818:Animals; D016207:Cytokines / Q000096:biosynthesis*; D015870:Gene Expression; D015847:Interleukin-4 / Q000096:biosynthesis*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis; D015375:Receptors, Interleukin-2 / Q000032:analysis; D016201:Receptors, Lymphocyte Homing / Q000032:analysis; D013154:Spleen / Q000166:cytology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology
chemical_list: D016207:Cytokines; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D015375:Receptors, Interleukin-2; D016201:Receptors, Lymphocyte Homing; D015847:Interleukin-4