Journal of Clinical Chemistry and Laboratory Medicine
Open Access

Immune Privilege Mechanism in Cornea

P.W.Ksander^{* *}Correspondence: P.W.Ksander, Department of Ophthalmology, UT Southwestern Medical Center at Dallas, Dallas, United States, Email:

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Description

Immune privilege refers to the ability of some bodily parts of mammals to tolerate the introduction of antigens without activating an inflammatory immune response. The immune system typically attacks tissue grafts because the body perceives them as foreign antigens. However, tissue transplants can endure for a long time without experiencing rejection in immune- privileged areas. The ocular immune system guards human eye against infection and controls the healing process after damage. The uvea, which is the area of the eye that houses many immune cells, primarily macrophages, dendritic cells, and mast cells, is highly vascularized but lack of lymphatic arteries. Immune privilege is a term used in transplantation. These cells protect the eyes from infections, and inflammation within the eye might appear as uveitis (including iritis) or retinitis. Immunologically speaking, the cornea of the eye is a particularly unique tissue. Due to its continual contact with the outside environment, it is open to a variety of bacteria, with the cornea being particularly vulnerable due to its wet mucosal surface. At the same time, immune protection is challenging due to its lack of vasculature and relative immunological isolation from the rest of the body. It serves as a barrier to prevent viruses from entering the rest of the eye, similar to how the dermis and epidermis protect underlying tissues. It contributes a significant portion of the eye's refractive power, requiring it to maintain exceptional transparency. Both the vascularized tissues around the cornea and the innate immune sensitive cells that live there contribute to immune responses in the cornea. The cornea's primary job is to transmit and refract light, which enables the production of sharp images on the retina's back. This is accomplished by highly organized collagen in the cornea, which is 30 nanometers in diameter and spaced 60 nanometers apart to lessen light scatter. Aside from a few dendritic cells, the tissue lacks vascularization, lymphoid cells, and other stress response. Innate immune responses protect against infections and toxins. They act as a main form of defence that is present from birth and offer an intrinsic barrier against corneal infection. The orbit and the eyelid, for instance, can protect against stressful events as well as outside debris that might include bacteria. Tears, epithelial cells, keratocytes, corneal nerves, the complement system, and interferons are also parts of the ocular innate immune system. Compared to innate immune responses, acquired immune responses are far more pathogen-specific. These cell-mediated processes are thought to be partially regulated by corneal Langerhans cells. These antigen- presenting Langerhans cells gather fragments of encroaching pathogens and use them to activate an immune response. Cell- mediated immune responses have a much slower onset but are more effective, yet they can harm nearby tissues and impair vision. The conjunctiva supplies nutrients to underlying and surrounding tissue and covers the sclera, or whites of the eyes, as well as the interiors of the eyelids. One of the vascularized tissues nearest to the cornea is the conjunctiva. As a result, it serves as the cornea's primary supply of immunological components. In addition to producing IgA like the lacrimal glands, the conjunctiva also contains mast cells, lymphocytes, neutrophilic granulocytes, macrophages, and other components of the broader mucosal immune system. The lipid, aqueous, and mucin layers make up the tear film. This aid in refraction by providing a smooth surface, lubricating eyelid movement, passively transferring gases like oxygen and carbon dioxide, and shielding the cornea. This final function is accomplished by the tear film's many layers working together. The moist environment created by tears shields corneal epithelial cells from drying out and deteriorating. Lysozymes, lactoferrins, lipocalin, and beta-lysine, which support pathogen defences such destruction of bacterial cell walls, inhibition of bacterial and viral binding, inflammation, and detoxification, are also present in the liquid layer of the tear film, giving it additional antibacterial capabilities. White blood cells can also be delivered to the corneal surface. It's interesting to note that some parts of the body exhibit a condition known as immune privilege. It follows that the body's typical inflammatory immunological response is constrained in this situation. Immune-privileged tissues contain immunoregulatory and immunotolerogenic regulatory systems. In order to prevent swelling and other tissue changes from impairing vision, the eye regulates its inflammatory immune response. The brain, testicles, placenta, and foetus are other areas with immune privilege. Ocular defenses depend on both innate and learned responses. The network of lymphoid cells that make up Mucosa-Associated Lymphoid Tissue (MALT) is one significant pathway in which both are included.

Conclusion

One of the rare body parts with immunological privilege is the eye. The eye becomes a good place for several types of study and therapy because of this immunological advantage. According to scientists, immune privilege serves to shield these vital regions from harm that could result from immune response-induced swelling and elevated temperatures. For instance, to examine the function that certain cell types known as stem cells play in the growth and healing of damaged tissue, scientists can transplant them into the eye. Compared to other regions of the body, the immune-privileged eye has a lower rejection risk for cells implanted there. Studies on eye using stem cell have indicated promise for the treatment of future blindness.