title: Regulation of 4-1BB expression by cell-cell interactions and the cytokines, interleukin-2 and interleukin-4.
abstract: 4-1BB expression increased gradually following T cell activation, and by day 3 post-stimulation with immobilized anti-CD3 (anti-CD3i) or concanavalin A (Con A), splenic T cells were routinely 35-45% 4-1BB+ by flow cytometric analysis. 4-1BB was expressed on activated CD8+, CD4+, CD28+ and CD45RB+ T cells. Optimal 4-1BB expression was seen by day 6 post-stimulation and was cell density dependent. When T cells were cultured for 6 days at 1 x 10(6)/well in a 24-well plate with anti-CD3i, 82% of the cells were 4-1BB+. In contrast, at lower cell densities (4 x 10(5), 2 x 10(5) and 1 x 10(5)), optimal 4-1BB expression was observed only if the cultures were supplemented with recombinant interleukin-2 (IL-2) or recombinant IL-4 (IL-4). In agreement, with these results, modes of inducing endogenous IL-2 production such as cross-linking the costimulatory molecule, CD28, or the addition of syngeneic accessory cells to T cells activated with anti-CD3i, resulted in high levels of 4-1BB expression. The addition of interleukin-1 alpha (IL-1 alpha) or interferon-gamma (IFN-gamma) did not increase 4-1BB expression on anti-CD3i-activated T cells. In addition, if T cells were incubated with IL-2, IL-4, IL-1 alpha, IFN-gamma or anti-CD28 alone, no 4-1BB expression was induced. T cells activated with soluble anti-CD3 (anti-CD3s) in the presence of IL-2, IL-4, or accessory cells, did not express higher levels of 4-1BB on their cell surface. These data suggest that initial events crucial for efficient T cell activation, such as signals delivered through the T cell receptor/CD3 complex and the CD28 molecule, are instrumental in regulating subsequent 4-1BB expression.
authors.forename: K E
authors.initials: KE
authors.lastname: Pollok
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
authors.forename: B S
authors.initials: BS
authors.lastname: Kwon
mesh_terms: D000818:Animals; D015703:Antigens, CD; D018106:CD28 Antigens / Q000502:physiology; D017252:CD3 Complex / Q000276:immunology; D002450:Cell Communication; D005260:Female; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology*; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D017475:Receptors, Nerve Growth Factor / Q000032:analysis*; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis*; D013601:T-Lymphocytes / Q000737:chemistry* / Q000502:physiology; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9
chemical_list: D015703:Antigens, CD; D018106:CD28 Antigens; D017252:CD3 Complex; D007375:Interleukin-1; D007376:Interleukin-2; D017475:Receptors, Nerve Growth Factor; D018124:Receptors, Tumor Necrosis Factor; C505715:Tnfrsf9 protein, mouse; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9; D015847:Interleukin-4; D007371:Interferon-gamma