TRANCE, a tumor necrosis factor family member critical for CD40 ligand-independent T helper cell activation

Abstract

CD40 ligand (CD40L), a tumor necrosis factor (TNF) family member, plays a critical role in antigen-specific T cell responses in vivo. CD40L expressed on activated CD4(+) T cells stimulates antigen-presenting cells such as dendritic cells, resulting in the upregulation of costimulatory molecules and the production of various inflammatory cytokines required for CD4(+) T cell priming in vivo. However, CD40L- or CD40-deficient mice challenged with viruses mount protective CD4(+) T cell responses that produce normal levels of interferon gamma, suggesting a CD40L/CD40-independent mechanism of CD4(+) T cell priming that to date has not been elucidated. Here we show that CD4(+) T cell responses to viral infection were greatly diminished in CD40-deficient mice by administration of a soluble form of TNF-related activation-induced cytokine receptor (TRANCE-R) to inhibit the function of another TNF family member, TRANCE. Thus, the TRANCE/TRANCE-R interaction provides costimulation required for efficient CD4(+) T cell priming during viral infection in the absence of CD40L/CD40. These results also indicate that not even the potent inflammatory microenvironment induced by viral infections is sufficient to elicit efficient CD4(+) T cell priming without proper costimulation provided by the TNF family (CD40L or TRANCE). Moreover, the data suggest that TRANCE/TRANCE-R may be a novel and important target for immune intervention.

Figure 1

(A) TRANCE expression is upregulated after T cell activation. Purified T cells were stimulated with anti-CD3 plus anti-CD28 and stained with TR-Fc or control hIgG1, followed by FITC-conjugated goat anti–human IgG (Fc-specific) F(ab′)₂ fragment (Jackson ImmunoResearch Laboratories). (B) TRANCE induces IL-12 production in mature DCs. Mature bone marrow–derived DCs were cultured for 18 h in the presence or absence of soluble TRANCE (1 μg/ml), then fixed in 2% PFA. After incubation in 0.5% saponin, the cells were stained with anti– IL-12 p35 (C18.2), anti–IL-12 p40 (C15.1) (solid line), or control rat IgG (dotted line) followed by anti–rat IgG-PE (Jackson ImmunoResearch Laboratories), and analyzed by FACS^®. In parallel experiments, soluble CD40L also induced IL-12 p35 and IL-12 p40, at levels quantitatively similar to those induced by soluble TRANCE (data not shown).

Figure 1

(A) TRANCE expression is upregulated after T cell activation. Purified T cells were stimulated with anti-CD3 plus anti-CD28 and stained with TR-Fc or control hIgG1, followed by FITC-conjugated goat anti–human IgG (Fc-specific) F(ab′)₂ fragment (Jackson ImmunoResearch Laboratories). (B) TRANCE induces IL-12 production in mature DCs. Mature bone marrow–derived DCs were cultured for 18 h in the presence or absence of soluble TRANCE (1 μg/ml), then fixed in 2% PFA. After incubation in 0.5% saponin, the cells were stained with anti– IL-12 p35 (C18.2), anti–IL-12 p40 (C15.1) (solid line), or control rat IgG (dotted line) followed by anti–rat IgG-PE (Jackson ImmunoResearch Laboratories), and analyzed by FACS^®. In parallel experiments, soluble CD40L also induced IL-12 p35 and IL-12 p40, at levels quantitatively similar to those induced by soluble TRANCE (data not shown).

Figure 2

(A) Blocking TRANCE does not affect isotype switching after LCMV infection. C57BL/6 mice (triangles) or CD40-deficient mice (circles) were infected with LCMV and treated with TR-Fc (filled symbols) or control hIgG1 (open symbols). LCMV-specific IgG Abs were assessed 14 d later by ELISA. One representative experiment of two is shown. (B–E) Blocking TRANCE does not affect GC formation after LCMV infection. C57BL/6 mice (B and C) and CD40-deficient mice (D and E) were infected with LCMV and treated with either TR-Fc (B and D) or control hIgG1 (C and E). The presence of GCs was assessed 14 d later in spleens by PNA staining. One representative experiment of two is shown.

Figure 2

(A) Blocking TRANCE does not affect isotype switching after LCMV infection. C57BL/6 mice (triangles) or CD40-deficient mice (circles) were infected with LCMV and treated with TR-Fc (filled symbols) or control hIgG1 (open symbols). LCMV-specific IgG Abs were assessed 14 d later by ELISA. One representative experiment of two is shown. (B–E) Blocking TRANCE does not affect GC formation after LCMV infection. C57BL/6 mice (B and C) and CD40-deficient mice (D and E) were infected with LCMV and treated with either TR-Fc (B and D) or control hIgG1 (C and E). The presence of GCs was assessed 14 d later in spleens by PNA staining. One representative experiment of two is shown.

Figure 3

Blocking TRANCE does not interfere with the induction of cytotoxic T cells but plays a role in the LCMV-specific CD4⁺ T cell responses. C57BL/6 mice (triangles) or CD40-deficient mice (circles) were infected with LCMV and treated with TR-Fc (filled symbols) or control hIgG1 (open symbols). (A) The presence of LCMV-specific cytotoxic T cells was assessed 8 d after infection using peptide p33– pulsed EL-4 cells as target cells. (B and C) Spleen cells were isolated 13 d later, and CD4⁺ T cells were purified and stimulated in vitro with LCMV-infected splenic APCs. (B) Proliferation was assessed 3 d later by [³H]thymidine incorporation. Results are shown as mean ± SEM for three mice per group. (C) Secretion of IFN-γ was assessed from culture supernatants by ELISA. Results are shown as mean ± SEM from three mice per group. Identical results were obtained with the LCMV-derived class II binding peptide 13 (data not shown). One representative experiment of two is shown.

Figure 3

Blocking TRANCE does not interfere with the induction of cytotoxic T cells but plays a role in the LCMV-specific CD4⁺ T cell responses. C57BL/6 mice (triangles) or CD40-deficient mice (circles) were infected with LCMV and treated with TR-Fc (filled symbols) or control hIgG1 (open symbols). (A) The presence of LCMV-specific cytotoxic T cells was assessed 8 d after infection using peptide p33– pulsed EL-4 cells as target cells. (B and C) Spleen cells were isolated 13 d later, and CD4⁺ T cells were purified and stimulated in vitro with LCMV-infected splenic APCs. (B) Proliferation was assessed 3 d later by [³H]thymidine incorporation. Results are shown as mean ± SEM for three mice per group. (C) Secretion of IFN-γ was assessed from culture supernatants by ELISA. Results are shown as mean ± SEM from three mice per group. Identical results were obtained with the LCMV-derived class II binding peptide 13 (data not shown). One representative experiment of two is shown.

Figure 4

LCMV-specific CD4⁺ T cell responses at a later time point. C57BL/6 mice (triangles) or CD40-deficient mice (circles) were infected with LCMV and treated with either TR-Fc (filled symbols) or control hIgG1 (open symbols). Spleen cells were isolated 30 d later, and CD4⁺ T cells were purified and stimulated in vitro with LCMV-infected splenic APCs. (A) Proliferation was assessed 3 d later by [³H]thymidine incorporation. Results are shown as mean ± SEM of triplicate values from pooled spleen cells of three mice per group. (B) Secretion of IFN-γ was assessed from culture supernatants by ELISA. Results are shown as mean ± SEM of triplicate values from pooled spleen cells of three mice per group. Identical results were obtained with the LCMV-derived class II binding peptide 13 (data not shown). One representative experiment of two is shown.

Figure 5

TRANCE plays a role in influenza virus–specific CD4⁺ T cell responses. CD40-deficient mice were infected with influenza virus and treated with either TR-Fc (filled circles) or control hIgG1 (open circles). Spleen cells were isolated 8 d later, and CD4⁺ T cells were purified and restimulated in vitro with UV light–inactivated influenza viruses. (A) Proliferation was assessed 3 d later by [³H]thymidine incorporation. Results are shown as mean ± SEM from triplicate values from pooled spleen cells of three mice per group. Background proliferation is subtracted. (B) Secretion of IFN-γ was assessed from culture supernatants by ELISA. Results are shown as mean ± SEM from three mice per group. Background is <2 U/ml. One representative experiment of three is shown.