Parenchymal Cells of the Eye
We have previously shown that autoreactive T cells vary greatly in disease-inducing capacity 56, 57 . Unfortunately, this is not always reflected by differences in the fine specificity of the cell response or the cytokine-producing pattern of the maximally activated T cells. Because of this, researchers are searching for other cellular and molecular features showing a better correlation with the pathogenic nature of the cells. For example, studies in our laboratory have shown that the degree to...
Each Layer of the Corneal Allograft
The different layers of the normal cornea display either immunogenicity or immune privilege. Moreover, the properties of one layer can influence the properties and fate of another layer. Khodadoust and Silverstein 26 conducted a series of experiments in which individual layers of the cornea from outbred rabbits were placed for 4 weeks at orthotopic sites in eyes of allodisparate rabbit hosts. The allogeneic corneal tissue was then removed and grafted back into the fellow eye of the original...
Corneal Immune Privilege
There are numerous active and passive mechanisms that contribute to corneal immune privilege via all three aspects of the immune reflex arc 5-7 . These include lack of blood and lymphatic vessels, reduced numbers of MHC class II-positive antigen-presenting cells, reduced corneal expression of MHC class I, expression of CD95 ligand, an immunosuppressive microenvironment a-melanocyte-stimulating hormone and vasoactive intestinal polypeptide and the fact that the cornea is part of the anterior...
Pathogenesis of Ocular Onchocerciasis
Microfilariae invade both the anterior and the posterior eye. In the latter case, they cause uveitis and chorioretinitis, resulting in loss of vision. In the anterior segment, they are present in the anterior chamber and cornea, where they cause sclerosing keratitis. Eyes from human cases of onchocerciasis are difficult to obtain and show only the late stages of disease however, in the cornea these manifest as an infiltrate of monocytic and granulocytic cells in the stroma, often surrounding...
Abstract Anq
Anterior chamber AC -associated immune deviation ACAID is a form of ocular-derived peripheral tolerance that helps to maintain the immune privilege of the eye by suppressing both the priming and elicitation of adaptive immune responses. ACAID is known to facilitate the survival of corneal grafts and suppression autoimmune uveitis in the eye. Intravenous inoculation of in vitro generated ACAID tolerance-inducing antigen presenting cells APCs treated with transforming growth factor-p2 tolerogenic...
References Eoo
1 Niederkorn JY Immunology and immunomodulation of corneal transplantation. Int Rev Immunol 2002 21 173-196. 2 Aiken-O'Neill P, Mannis MJ Summary of corneal transplant activity Eye Bank Association of America. Cornea 2002 21 1-3. 3 Zirm E Eine erfolgreiche totale Keratoplastik. Graefes Arch Ophthalmol 1906 64 580-593. 4 Niederkorn JY The immune privilege of corneal grafts. J Leukoc Biol 2003 74 167-171. 5 Auchincloss H Jr, Mayer T, Ghobrial R, Winn HJ T-cell subsets, bm mutants, and the...
Angiogenic Privilege 1
Novel insights into the molecular mechanisms of hem- and lymphangio-genesis explain the close interrelations between neovascularization and immunity inflammation. Most mediators of angiogenesis, e.g. vascular endothelial growth factor VEGF , which have traditionally been thought of as acting solely on vascular endothelium, also have profound effects on immune and inflammatory reactions. For example, VEGF-A via its receptor 1 VEGFR1 is a potent chemoattractant for macrophages 3, 10 . VEGF-C, in...
The Role of Mast Cells
Mast cell activation results from a multivalent allergen cross-linking cell surface IgE with high affinity FceRI mast cell receptors 9 . Conjunctival mast cell activation leads to the release of histamine and locally synthesized mediators, e.g. prostaglandin D2, leukotriene C4, tryptase, chymase, carboxypeptidase A, cathepsin G, and platelet-activating factor, a powerful eosinophil chemotactic agent and other eosinophil and neutrophil chemoattractants. Allergen challenge in atopic patients...
The Anatomy of the Eye
Immune privilege of the eye involves the globe and its contents. Thus, only a passing reference will be made to the orbit and eyelids. The orbit is the bony, concave cavity in the skull that houses the globe, extraocular muscles, blood vessels and nerves of the eye. There is a very thin orbital floor consisting of the maxillary, palatine, and zygomatic bones , a medial wall consisting of the frontal process of the maxilla, lacrimal bone, orbital plate of the frontal bone, and lesser wing of the...
The Revival of Immune Surveillance
Experimental support of immune surveillance began to emerge in the middle 1990s with the development and testing of a variety of mutant mice that were deficient in one or more components of innate or adaptive immune systems. The first evidence came from a series of experimental models that eliminated interferon IFN -7, an important cytokine produced mainly by T cells, natural killer NK cells, and NKT cells. Mice treated with neutralizing antibodies for IFN-7 and then given transplanted...
Immune Privilege of the Brain
Multiple sites in the body express varying degrees of immune privilege including the anterior chamber of the eye, brain, hamster cheek pouch, hair follicle, and pregnant uterus. The earliest explanation for the immune privilege of the brain suggested that the absence of conventional lymphatic vessels prevented antigens from leaving the brain and reaching regional lymph nodes, and the tight junctions between vascular endothelial cells in the brain created a blood-brain barrier that retarded...
Clinical Features of Acute Retinal Necrosis
Although numerous clinical findings have been described, none is pathog-nomonic for ARN. Keratic precipitates that usually appear as white, mutton fat deposits often occur during the onset of HSV or VZV ARN. In the chronic phase, white mutton fat-like precipitates may be replaced by pigmented precipitates fig. 1 . Although anterior granulomatous uveitis is ameliorated within 2 weeks, resolution of the prominent vitritis tends to be delayed compared to the anterior uveitis. The prominent vitreal...
The Clinical Problem
Infectious versus Non-Infectious Disease Since many of the posterior uveitic conditions present with a somewhat restricted set of overlapping clinical signs and symptoms, the major clinical dilemma is to decide whether the disease is infectious or non-infectious table 1 . This has important therapeutic implications since many infectious diseases can be worsened by inappropriate use of immunosuppressants, while on the other Table 1. Classification of posterior segment intraocular inflammation...
References Vgp
1 Streilein JW Ocular immune privilege therapeutic opportunities from an experiment of nature. Nat Rev Immunol 2003 3 879-889. 2 Streilein JW Ocular immune privilege the eye takes a dim but practical view of immunity and inflammation. J Leukoc Biol 2003 74 179-185. 3 Cursiefen C, Kruse FE New aspects of corneal angiogenesis in Reinhard T, Larkin F eds Cornea and External Eye in Krieglstein GK, Weinreb RN ser eds Essentials in Ophthalmology. New York, Springer, 2006, pp 83-99. 4 Chang JH,...
Complement and the Eye
Role in the Induction of Anterior Chamber-Associated The unique immunologic and anatomic features of the eye prevent the induction and expression of conventional immunity - a phenomenon known as 'immune privilege'. Immune privilege in the eye is a dynamic state in which the systemic immune response to antigens introduced intraocularly is aberrant, resulting in antigen-specific suppression of the delayed-type hypersensitivity response - a phenomenon referred to as AC-associated immune deviation...
The Immunoediting Hypothesis
Dunn et al. 27 recently proposed the immunoediting hypothesis which they considered an extension of the immune surveillance theory that explained situations in which immune surveillance failed to protect the host from malignant transformation. It is obvious that, even in an immune-competent host, spontaneous tumors still develop. This means that although immune surveillance is fully functional, some tumors still escape immune detection and grow progressively. Thus, immune surveillance appeared...
Abstract Ngm
Corneal allografts enjoy a remarkable success rate when compared to all other forms of organ transplants. In routine keratoplasties, HLA matching and systemic immunosuppressive drugs are not employed, yet 90 of the uncomplicated transplants survive. The success of corneal allografts was recognized over half a century ago and led to the term 'immune privilege'. The original explanation for the immune privilege of corneal allografts attributed the escape of immune rejection to the avascular and...
Anterior Uveitis
As mentioned, AU is a term which refers to inflammation within the anterior segment of the eye and can be further subdivided anatomically into either iritis and or iridocyclitis. It is the most common form of uveitis and accounts for approximately 75 of cases. Inflammation occurs in either the iris or the CB, with spillover of vitreous inflammatory cells into the space behind the lens. Retinal involvement is not a component of AU 14, 15 . A single episode of AU does not cause permanent visual...