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Iris pigment epithelium expressing CD86 (B7-2) directly suppresses T cell activation in vitro via binding to cytotoxic T lymphocyte-associated antigen 4.

Sugita S, Streilein JW - J. Exp. Med. (2003)

Bottom Line: When IPE were blocked with anti-CD86 or were derived from CD80/CD86 (but not CD80) knockout (KO) mice, the cells displayed reduced capacity to suppress T cell activation.IPE also failed to suppress activation of T cells in the presence of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) immunoglobulin or if the T cells were obtained from CTLA-4 (but not CD28) KO mice.Thus, ocular immune privilege is achieved in part by subversion of molecules that are usually used for conventional immune costimulation.

View Article: PubMed Central - PubMed

Affiliation: Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA.

ABSTRACT
A monolayer of pigment epithelium (PE) lines the iris PE (IPE), ciliary body PE, and retina PE of the inner eye, an immune-privileged site. These neural crest-derived epithelial cells participate in ocular immune privilege through poorly defined molecular mechanisms. Murine PE cells cultured from different ocular tissues suppress T cell activation by differing mechanisms. In particular, IPE cells suppress primarily via direct cell to cell contact. By examining surface expression of numerous candidate molecules (tumor necrosis factor receptor [TNFR]1, TNFR2, CD36, CD40, CD47, CD80, CD86, PD-L1, CD95 ligand, and type I interferon receptor), we report that IPE cells uniquely express on their surface the costimulatory molecule CD86. When IPE were blocked with anti-CD86 or were derived from CD80/CD86 (but not CD80) knockout (KO) mice, the cells displayed reduced capacity to suppress T cell activation. IPE also failed to suppress activation of T cells in the presence of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) immunoglobulin or if the T cells were obtained from CTLA-4 (but not CD28) KO mice. We conclude that iris pigment epithelial cells constitutively express cell surface CD86, which enables the cells to contact inhibit T cells via direct interaction with CTLA-4. Thus, ocular immune privilege is achieved in part by subversion of molecules that are usually used for conventional immune costimulation.

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Capacity of ocular PE to suppress activation of T cells from mice with disrupted CD28 and CTLA-4 (CD152) genes. PE were cultured from iris, ciliary body, and retina of C57BL/6 mice and used as substrates for purified T cells prepared from the spleens of 22-d-old wild-type mice, 22-d-old CTLA-4−/− mice, and 6-wk-old CD28−/− mice. The T cells were stimulated with anti-CD3 antibodies at concentrations of (A) 0.5 and (B) 1.0 μg/ml. Cultures were terminated at 72 h and [3H]thymidine incorporation was assessed. Mean counts per minute for triplicate cultures are presented ± SEM. Differences of means of T cell proliferation in the presence or absence of PE cells are compared. *, P < 0.05; **, P < 0.005; ***, P < 0.0005; NS, not significant.
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fig8: Capacity of ocular PE to suppress activation of T cells from mice with disrupted CD28 and CTLA-4 (CD152) genes. PE were cultured from iris, ciliary body, and retina of C57BL/6 mice and used as substrates for purified T cells prepared from the spleens of 22-d-old wild-type mice, 22-d-old CTLA-4−/− mice, and 6-wk-old CD28−/− mice. The T cells were stimulated with anti-CD3 antibodies at concentrations of (A) 0.5 and (B) 1.0 μg/ml. Cultures were terminated at 72 h and [3H]thymidine incorporation was assessed. Mean counts per minute for triplicate cultures are presented ± SEM. Differences of means of T cell proliferation in the presence or absence of PE cells are compared. *, P < 0.05; **, P < 0.005; ***, P < 0.0005; NS, not significant.

Mentions: Next, we inquired into the nature of the costimulation receptor that is present on T cells and which upon binding to CD86 delivers a negative signal for activation. For these experiments we used mice with disrupted genes for CD28 or CD152 (CTLA-4). PE cells were cultured as before from iris, ciliary body, and retina and placed in culture wells. Purified splenic T cells were then prepared from CTLA-4−/−, CD28−/−, and wild-type control mice and added to these wells. The T cells were then stimulated with anti-CD3 antibodies at two different concentrations, 0.5 and 1.0 μg/ml, and proliferation was assessed by triturated thymidine uptake. CD28−/− T cells were as profoundly suppressed as wild-type T cells when exposed to IPE, CBPE, and RPE (Fig. 8). By contrast, CTLA-4−/− T cells proliferated when exposed to IPE, but not when exposed to CBPE and RPE. In fact, T cells from CTLA-4 KO mice that were stimulated with 0.5 μg/ml anti-CD3 in the presence of IPE cells proliferated almost to the same extent as did similar T cells exposed to anti-CD3 in the absence of IPE. Together, these results indicate that IPE constitutively express CD86 and this molecule binds directly to CTLA-4 on T cells, thereby changing the T cells' functional program and suppressing their susceptibility to activation through the T cell receptor.


Iris pigment epithelium expressing CD86 (B7-2) directly suppresses T cell activation in vitro via binding to cytotoxic T lymphocyte-associated antigen 4.

Sugita S, Streilein JW - J. Exp. Med. (2003)

Capacity of ocular PE to suppress activation of T cells from mice with disrupted CD28 and CTLA-4 (CD152) genes. PE were cultured from iris, ciliary body, and retina of C57BL/6 mice and used as substrates for purified T cells prepared from the spleens of 22-d-old wild-type mice, 22-d-old CTLA-4−/− mice, and 6-wk-old CD28−/− mice. The T cells were stimulated with anti-CD3 antibodies at concentrations of (A) 0.5 and (B) 1.0 μg/ml. Cultures were terminated at 72 h and [3H]thymidine incorporation was assessed. Mean counts per minute for triplicate cultures are presented ± SEM. Differences of means of T cell proliferation in the presence or absence of PE cells are compared. *, P < 0.05; **, P < 0.005; ***, P < 0.0005; NS, not significant.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2196085&req=5

fig8: Capacity of ocular PE to suppress activation of T cells from mice with disrupted CD28 and CTLA-4 (CD152) genes. PE were cultured from iris, ciliary body, and retina of C57BL/6 mice and used as substrates for purified T cells prepared from the spleens of 22-d-old wild-type mice, 22-d-old CTLA-4−/− mice, and 6-wk-old CD28−/− mice. The T cells were stimulated with anti-CD3 antibodies at concentrations of (A) 0.5 and (B) 1.0 μg/ml. Cultures were terminated at 72 h and [3H]thymidine incorporation was assessed. Mean counts per minute for triplicate cultures are presented ± SEM. Differences of means of T cell proliferation in the presence or absence of PE cells are compared. *, P < 0.05; **, P < 0.005; ***, P < 0.0005; NS, not significant.
Mentions: Next, we inquired into the nature of the costimulation receptor that is present on T cells and which upon binding to CD86 delivers a negative signal for activation. For these experiments we used mice with disrupted genes for CD28 or CD152 (CTLA-4). PE cells were cultured as before from iris, ciliary body, and retina and placed in culture wells. Purified splenic T cells were then prepared from CTLA-4−/−, CD28−/−, and wild-type control mice and added to these wells. The T cells were then stimulated with anti-CD3 antibodies at two different concentrations, 0.5 and 1.0 μg/ml, and proliferation was assessed by triturated thymidine uptake. CD28−/− T cells were as profoundly suppressed as wild-type T cells when exposed to IPE, CBPE, and RPE (Fig. 8). By contrast, CTLA-4−/− T cells proliferated when exposed to IPE, but not when exposed to CBPE and RPE. In fact, T cells from CTLA-4 KO mice that were stimulated with 0.5 μg/ml anti-CD3 in the presence of IPE cells proliferated almost to the same extent as did similar T cells exposed to anti-CD3 in the absence of IPE. Together, these results indicate that IPE constitutively express CD86 and this molecule binds directly to CTLA-4 on T cells, thereby changing the T cells' functional program and suppressing their susceptibility to activation through the T cell receptor.

Bottom Line: When IPE were blocked with anti-CD86 or were derived from CD80/CD86 (but not CD80) knockout (KO) mice, the cells displayed reduced capacity to suppress T cell activation.IPE also failed to suppress activation of T cells in the presence of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) immunoglobulin or if the T cells were obtained from CTLA-4 (but not CD28) KO mice.Thus, ocular immune privilege is achieved in part by subversion of molecules that are usually used for conventional immune costimulation.

View Article: PubMed Central - PubMed

Affiliation: Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA.

ABSTRACT
A monolayer of pigment epithelium (PE) lines the iris PE (IPE), ciliary body PE, and retina PE of the inner eye, an immune-privileged site. These neural crest-derived epithelial cells participate in ocular immune privilege through poorly defined molecular mechanisms. Murine PE cells cultured from different ocular tissues suppress T cell activation by differing mechanisms. In particular, IPE cells suppress primarily via direct cell to cell contact. By examining surface expression of numerous candidate molecules (tumor necrosis factor receptor [TNFR]1, TNFR2, CD36, CD40, CD47, CD80, CD86, PD-L1, CD95 ligand, and type I interferon receptor), we report that IPE cells uniquely express on their surface the costimulatory molecule CD86. When IPE were blocked with anti-CD86 or were derived from CD80/CD86 (but not CD80) knockout (KO) mice, the cells displayed reduced capacity to suppress T cell activation. IPE also failed to suppress activation of T cells in the presence of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) immunoglobulin or if the T cells were obtained from CTLA-4 (but not CD28) KO mice. We conclude that iris pigment epithelial cells constitutively express cell surface CD86, which enables the cells to contact inhibit T cells via direct interaction with CTLA-4. Thus, ocular immune privilege is achieved in part by subversion of molecules that are usually used for conventional immune costimulation.

Show MeSH
Related in: MedlinePlus