Participation of pigment epithelium of iris and ciliary body in ocular immune privilege. 2. Generation of TGF-beta-producing regulatory T cells.
OBJECTIVE
To determine whether T cells exposed to cultured iris and ciliary body pigment epithelial (I/CB PE) cells acquire the capacity to modify the activation, differentiation, and effector functions of bystander T cells, and if so, to identify the mechanism.


METHODS
T cells from naive BALB/c mice were cultured with I/CB PE cells, x-irradiated, and used as regulators (a) of T-cell activation in vitro and (b) of delayed hypersensitivity expression in vivo. Neutralizing anti-TGF-beta and -IL-10 antibodies were used to abolish regulatory function. T-cell activation was assessed for proliferation by [(3)H]thymidine incorporation and for IL-2, IFN-gamma, IL-4, and IL-10 production by semi-quantitative RT-PCR for mRNA and by supernatant analysis by ELISA. I/CB PE-exposed T cells were evaluated for mRNA content of IFN-gamma, IL-4, TNF-alpha, TGF-beta1, TGF-beta2, and IL-10, and their supernatants were analyzed for content of TGF-beta.


RESULTS
T cells exposed to I/CB PE cells inhibited anti-CD3-driven activation of bystander naive T cells in vitro and suppressed the expression of delayed hypersensitivity in vivo. Bystander T cells cocultured with I/CB PE-exposed T cells failed to proliferate and secreted high levels of IL-4 and IL-10 but low amounts of IL-2 and IFN-gamma. Regulation of bystander T-cell activation was mediated via enhanced secretion of TGF-beta by I/CB PE-exposed T cells.


CONCLUSIONS
T cells exposed to cultured I/CB PE cells were induced to secrete active and latent TGF-beta, which conferred on the T cells the capacity to inhibit the differentiation as well as the effector function of Th1-type cells.
Yoshida
M
M
Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA.
Kezuka
T
T
Streilein
J W
JW
D000818:Animals; D017252:CD3 Complex / Q000276:immunology; D002454:Cell Differentiation; D002478:Cells, Cultured; D002924:Ciliary Body / Q000166:cytology / Q000502:physiology*; D018920:Coculture Techniques; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D017931:DNA Primers / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay; D006968:Hypersensitivity, Delayed / Q000276:immunology / Q000517:prevention & control; D016130:Immunophenotyping; D007498:Iris / Q000166:cytology / Q000502:physiology*; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000276:immunology*; D016212:Transforming Growth Factor beta / Q000096:biosynthesis*
D017252:CD3 Complex; D016207:Cytokines; D017931:DNA Primers; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta