Limits...
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.

Show MeSH

Related in: MedlinePlus

Influence of CTLA-4–Ig on suppression of T cell activation by ocular PE. PE cells were cultured from iris, ciliary body, and retina of C57BL/6 mice. IPE served as substrates for purified T cells stimulated with anti-CD3 antibodies in the presence of varying concentrations of CTLA-4–Ig. 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 CTLA-4–Ig are compared. *, P < 0.05.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2196085&req=5

fig7: Influence of CTLA-4–Ig on suppression of T cell activation by ocular PE. PE cells were cultured from iris, ciliary body, and retina of C57BL/6 mice. IPE served as substrates for purified T cells stimulated with anti-CD3 antibodies in the presence of varying concentrations of CTLA-4–Ig. 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 CTLA-4–Ig are compared. *, P < 0.05.

Mentions: CD86 is a costimulation molecule that is expressed on APCs and through binding to CD28 provides a key activation signal to T cells. CD86 also binds CTLA-4 on T cells, in which case the T cells are negatively signaled and acquire anergic and even regulatory properties. CTLA-4–Ig is a fusion protein that binds to CD86 with very high affinity and is able to thwart CD28-dependent T cell activation. In the following experiments, we tested the effect of CTLA-4–Ig on the activation of T cells exposed in vitro to IPE and stimulated with anti-CD3. As before, purified splenic T cells were placed in culture wells containing cultured IPE and stimulated with anti-CD3 antibodies in the presence of CTLA-4–Ig over a concentration range of 5.0–0.001 μg/ml. T cell proliferation was measured at 72 h by triturated thymidine uptake. As the results displayed in Fig. 7 reveal, above a concentration of 0.5 μg/ml CTLA-4–Ig, T cells exposed to IPE underwent significant levels of proliferation. In addition, IPE cells failed to suppress T cell activation with allogeneic spleen cells (not depicted). Similar experiments performed with anti–CD3-stimulated T cells exposed to CBPE or RPE in the presence of CTLA-4–Ig failed to reveal T cell proliferation (not depicted). These findings indicate that blocking of interactions between CD86 on IPE cells and coreceptors on T cells partially relieves the contact-dependent suppression mediated by IPE cells.


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)

Influence of CTLA-4–Ig on suppression of T cell activation by ocular PE. PE cells were cultured from iris, ciliary body, and retina of C57BL/6 mice. IPE served as substrates for purified T cells stimulated with anti-CD3 antibodies in the presence of varying concentrations of CTLA-4–Ig. 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 CTLA-4–Ig are compared. *, P < 0.05.
© Copyright Policy
Related In: Results  -  Collection

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

fig7: Influence of CTLA-4–Ig on suppression of T cell activation by ocular PE. PE cells were cultured from iris, ciliary body, and retina of C57BL/6 mice. IPE served as substrates for purified T cells stimulated with anti-CD3 antibodies in the presence of varying concentrations of CTLA-4–Ig. 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 CTLA-4–Ig are compared. *, P < 0.05.
Mentions: CD86 is a costimulation molecule that is expressed on APCs and through binding to CD28 provides a key activation signal to T cells. CD86 also binds CTLA-4 on T cells, in which case the T cells are negatively signaled and acquire anergic and even regulatory properties. CTLA-4–Ig is a fusion protein that binds to CD86 with very high affinity and is able to thwart CD28-dependent T cell activation. In the following experiments, we tested the effect of CTLA-4–Ig on the activation of T cells exposed in vitro to IPE and stimulated with anti-CD3. As before, purified splenic T cells were placed in culture wells containing cultured IPE and stimulated with anti-CD3 antibodies in the presence of CTLA-4–Ig over a concentration range of 5.0–0.001 μg/ml. T cell proliferation was measured at 72 h by triturated thymidine uptake. As the results displayed in Fig. 7 reveal, above a concentration of 0.5 μg/ml CTLA-4–Ig, T cells exposed to IPE underwent significant levels of proliferation. In addition, IPE cells failed to suppress T cell activation with allogeneic spleen cells (not depicted). Similar experiments performed with anti–CD3-stimulated T cells exposed to CBPE or RPE in the presence of CTLA-4–Ig failed to reveal T cell proliferation (not depicted). These findings indicate that blocking of interactions between CD86 on IPE cells and coreceptors on T cells partially relieves the contact-dependent suppression mediated by IPE cells.

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