Streilein J W, Bradley D
Department of Microbiology and Immunology, University of Miami School of Medicine, FL 33101.
Invest Ophthalmol Vis Sci. 1991 Sep;32(10):2700-10.
The anterior chamber of the eye is an immunosuppressive microenvironment as shown experimentally by immune privilege, anterior chamber-associated immune deviation, and inability to display local delayed-type hypersensitivity responses. It recently was reported that both the aqueous humor and the cells of the iris and ciliary body (I-CB) have immune inhibitory properties in vitro, suggesting that these components of the anterior segment might contribute to the unique properties of this microenvironment. To explore the cellular sources of immunosuppressive factors in the anterior chamber, cultures of I-CB cells were established from normal eyes of BALB/c mice. Supernatants were harvested from these cultures and assayed in vitro for their ability to inhibit T-lymphocyte activation. It was found that I-CB cell-derived supernatants profoundly suppressed alloantigen-driven T-cell proliferation (mixed lymphocyte response) and interleukin-2 production by a T-cell hybridoma that responds to stimulator cells bearing I-Ad. The inhibitory activity of I-CB supernatants did not appear to be related to prostaglandins; supernatants of I-CB cells cultured with indomethacin retained their suppressive properties, as did supernatants to which neutralizing antiprostaglandin E2 antibodies had been added. Moreover, suppression by I-CB supernatants was not relieved by antibodies specific for transforming growth factor-beta, even though this cytokine is known to be present in normal aqueous humor. Thus, the identity of the suppressive factor(s) in cultured I-CB cell supernatants remains elusive. Finally, by separating I-CB cell suspensions into bone marrow-derived (T-200-positive) and those not derived from bone marrow (parenchymal) subpopulations with a fluorescence-activated cell sorter, it was determined that the inhibitory activity of I-CB cell suspensions was produced by parenchymal, rather than hematogenous, cells. It is proposed and discussed that inhibitory factors and cytokines secreted by parenchymal I-CB cells contribute to the immunosuppressive qualities of the anterior chamber.
眼的前房是一个免疫抑制性微环境，这已通过免疫赦免、前房相关免疫偏离以及无法表现出局部迟发型超敏反应等实验得到证明。最近有报道称，房水以及虹膜和睫状体（I-CB）的细胞在体外均具有免疫抑制特性，这表明眼前节的这些成分可能促成了该微环境的独特性质。为了探究前房免疫抑制因子的细胞来源，从BALB/c小鼠的正常眼睛中建立了I-CB细胞培养物。从这些培养物中收集上清液，并在体外检测其抑制T淋巴细胞活化的能力。结果发现，I-CB细胞来源的上清液能显著抑制同种异体抗原驱动的T细胞增殖（混合淋巴细胞反应）以及对携带I-Ad刺激细胞有反应的T细胞杂交瘤产生白细胞介素-2。I-CB上清液的抑制活性似乎与前列腺素无关；用吲哚美辛培养的I-CB细胞的上清液保留了其抑制特性，添加了中和抗前列腺素E2抗体的上清液也是如此。此外，尽管已知这种细胞因子存在于正常房水中，但针对转化生长因子-β的特异性抗体并不能消除I-CB上清液的抑制作用。因此，培养的I-CB细胞上清液中抑制因子的身份仍然难以捉摸。最后，通过用荧光激活细胞分选仪将I-CB细胞悬液分离为骨髓来源（T-200阳性）和非骨髓来源（实质）亚群，确定I-CB细胞悬液的抑制活性是由实质细胞而非造血细胞产生的。有人提出并讨论了实质I-CB细胞分泌的抑制因子和细胞因子促成了前房的免疫抑制特性。
