Immunology of the Eye

Study Flashcards Play Quiz

Questions and Answers

What is the mechanism of immune privilege that prevents the passage of cells from the blood to the anterior eye?

Tight junctions between cells

The eye has a well-developed lymphatic drainage system.

False

What is the result of exposure of the anterior chamber to a foreign antigen?

Induction of suppressor immunity

Anterior chamber-associated immune deviation (ACAID) is mediated by specific _______________ and NKT cells.

macrophages Signup and view all the answers

What is the function of immunosuppressive molecules in the eye?

To inhibit T-cell proliferation Signup and view all the answers

Match the following mechanisms of immune privilege with their descriptions:

Anatomical features = Protected by conjunctiva and eyelids Lack of lymphatic drainage = Prevents antigen presentation to immune cells Immunosuppressive molecules = Inhibit T-cell proliferation and suppress interferon secretion Development of tolerance = Induces suppressor immunity Signup and view all the answers

The eye has a high expression of major histocompatibility (MHC) molecules.

False Signup and view all the answers

What is the result of induction of antigen-specific suppressor CD8+ T-cells and regulatory T-cells?

Suppressor immunity Signup and view all the answers

What is the mechanism by which the host epithelium responds to a graft in epithelial rejection?

The host epithelium grows inward from the remaining host cornea and limbus, covering the graft Signup and view all the answers

The presence of bone marrow-derived cells in the host cornea at the time of surgery contributes to a lower rejection rate.

False Signup and view all the answers

What is the primary function of the immune cells recruited into the cornea through limbal circulation?

To process and present antigens Signup and view all the answers

What is the result of the proliferation of T-regulatory cells specific to the antigen?

Suppresses the delayed type hypersensitivity (Type IV) response Signup and view all the answers

Corneal transplantation is not a successful procedure.

False Signup and view all the answers

The capacity of the graft to induce _______________________ is a mechanism that contributes to immune privilege.

anterior chamber-associated immune deviation (ACAID) Signup and view all the answers

Which type of rejection is characterized by subepithelial infiltrates with leukocytes?

Subepithelial rejection Signup and view all the answers

What is the main reason for avoiding immune response in the eye?

To prevent dysfunction, such as loss of vision, due to inflammation Signup and view all the answers

What is the role of the aqueous humor in maintaining immune privilege in the eye?

It creates an immunosuppressive local microenvironment Signup and view all the answers

The absence of __________ vessels in the graft and its bed contributes to immune privilege.

blood and lymph Signup and view all the answers

Match the following immune response mechanisms with their functions:

Anterior Chamber-associated Immune Deviation = Suppresses immune response in the eye Mechanisms Of Immune Privilege = Prevents inflammation in the eye Lymphatic Drainage In The Eye = Drains excess fluids from the eye Immunosuppressive Molecules = Suppresses the immune response Signup and view all the answers

Match the following types of rejection with their characteristics:

Epithelial rejection = Host epithelium grows inward from remaining host cornea and limbus Subepithelial rejection = Subepithelial infiltrates with leukocytes Both types of rejection = Steroid responsive, generally self-limited, and tend not to cause visual disturbance Signup and view all the answers

The presence of MHC-antigens on graft cells enhances immune privilege in the eye.

False Signup and view all the answers

What is the name of the surgical procedure that involves replacing the diseased or damaged cornea with a healthy donor cornea?

All of the above Signup and view all the answers

The eye has a well-developed lymphatic drainage system.

False Signup and view all the answers

What is the indication for corneal transplantation when the cornea is likely to break open?

Severe scarring of cornea Signup and view all the answers

What is the primary function of immune privilege?

To protect vital structures from the potentially damaging effects of an inflammatory immune response Signup and view all the answers

The anterior chamber is not immune privileged.

False Signup and view all the answers

What is an allograft?

A transplant of an organ or tissue from one individual to another of the same species with a different genotype. Signup and view all the answers

The eye is protected from immune reactions that are potentially dangerous in the _______________________ chamber.

anterior Signup and view all the answers

Which of the following is NOT an example of an immune privileged site?

Lungs Signup and view all the answers

Corneal graft rejection is a major concern in eye transplantation.

True Signup and view all the answers

Match the following immune privileged sites with their characteristics:

Eyes = Protected from immune reactions that are potentially dangerous Placenta and fetus = Immune responses directed against a fetus can lead to the loss of the fetus Brain = Inflammation in the brain can lead to loss of organ function Testicles = Hair growth is promoted Signup and view all the answers

What is the purpose of immune privilege in the eye?

To protect the eye from the potentially damaging effects of an inflammatory immune response. Signup and view all the answers

What is the primary mechanism of direct pathway in corneal graft rejection?

Donor's APCs are recognised directly by recipient's T-cells Signup and view all the answers

Corneal graft rejection is always symptomatic.

False Signup and view all the answers

What are the two mechanisms of corneal graft rejection?

Direct pathway and indirect pathway Signup and view all the answers

The indirect pathway of corneal graft rejection leads to ______ hypersensitivity.

Delayed (Type IV) Signup and view all the answers

Match the following risk factors with their corresponding descriptions:

Host corneal vascularisation = Lower risk with this age group Larger and eccentric grafts = Increased risk of graft rejection Presence of donor epithelium upon transplantation = Increased risk of graft rejection due to presence of donor cells Age > 60 years = Increased risk of graft rejection due to increased blood supply Signup and view all the answers

What is the primary site of antigen processing in corneal graft rejection?

At cornea, ocular environments, and draining lymph nodes Signup and view all the answers

ABO blood type incompatibility is a confirmed risk factor for corneal graft rejection.

False Signup and view all the answers

What is the common complaint associated with corneal graft rejection?

Decrease in visual acuity, redness, pain, irritation, and photophobia Signup and view all the answers

Study Notes

Mechanisms of Immune Privilege

Lack of lymphatic drainage in the eye
Anatomical features: blood barrier, no blood vessels or inflammatory cells, protected by conjunctiva and eyelids
Presence of immunosuppressive molecules or cell surface receptors that inhibit T-cell proliferation and suppress interferon secretion
Lower expression of major histocompatibility (MHC) molecules
Development of tolerance against antigens through anterior chamber-associated immune deviation (ACAID)

Anterior Chamber-Associated Immune Deviation (ACAID)

Exposure of the anterior chamber to a foreign antigen induces suppressor immunity
Induction of antigen-specific suppressor CD8+ T-cells and regulatory T-cells (suppressor CD4+ T-cells)
Induction of non-complement-fixing antibodies mediated by specific macrophages
Presentation of inoculated antigen to a cluster of B-cells, NKT cells, CD4+ and CD8+ T cells in the spleen

Corneal Graft Rejection

Types of rejection: epithelial, subepithelial, and both types
Immune mechanism: inflamed cornea contributes to erosion of immune privilege
Bone marrow-derived cells are recruited into cornea through limbal circulation
These cells can process and present antigens, leading to rejection

Why Immune Privilege?

Normal symptoms of inflammation (redness, swelling, and pain) can lead to dysfunction in the eye (loss of vision)
Certain circumstances (e.g., trauma, infection, genetics) can lead to dysfunction of the regulatory mechanisms of the eye, leading to immune inflammatory diseases

Corneal Transplantation

Also known as penetrating keratoplasty
Over 40,000 procedures done per year in the USA
Indications: severe scarring of cornea, cornea likely to break open, severe damage involving cornea and lens
Corneas are removed from donors who have been declared dead

Why is Corneal Transplantation Successful?

Due to corneal immune privilege
Absence of blood and lymph vessels in the graft and its bed
Absence of MHC class II+ antigen presenting cells in the graft

Risk Factors for Corneal Graft Rejection

Host corneal vascularisation
Larger and eccentric grafts
Presence of donor epithelium upon transplantation
History of previous graft failure of any cause
Bilateral penetrating keratoplasty
Pre-transplantation corneal tissue media and preservation
Host age (lower risk with age >60 y, much higher risk in infants)
Human leukocyte antigen A (HLA-A) and human leukocyte antigen (HLA-B) and ABO blood type incompatibility

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Immunology of the Eye

Questions and Answers

What is the mechanism of immune privilege that prevents the passage of cells from the blood to the anterior eye?

The eye has a well-developed lymphatic drainage system.

What is the result of exposure of the anterior chamber to a foreign antigen?

Anterior chamber-associated immune deviation (ACAID) is mediated by specific _______________ and NKT cells.

What is the function of immunosuppressive molecules in the eye?

Match the following mechanisms of immune privilege with their descriptions:

The eye has a high expression of major histocompatibility (MHC) molecules.

What is the result of induction of antigen-specific suppressor CD8+ T-cells and regulatory T-cells?

What is the mechanism by which the host epithelium responds to a graft in epithelial rejection?

The presence of bone marrow-derived cells in the host cornea at the time of surgery contributes to a lower rejection rate.

What is the primary function of the immune cells recruited into the cornea through limbal circulation?

What is the result of the proliferation of T-regulatory cells specific to the antigen?

Corneal transplantation is not a successful procedure.

The capacity of the graft to induce _______________________ is a mechanism that contributes to immune privilege.

Which type of rejection is characterized by subepithelial infiltrates with leukocytes?

What is the main reason for avoiding immune response in the eye?

What is the role of the aqueous humor in maintaining immune privilege in the eye?

The absence of __________ vessels in the graft and its bed contributes to immune privilege.

Match the following immune response mechanisms with their functions:

Match the following types of rejection with their characteristics:

The presence of MHC-antigens on graft cells enhances immune privilege in the eye.

What is the name of the surgical procedure that involves replacing the diseased or damaged cornea with a healthy donor cornea?

The eye has a well-developed lymphatic drainage system.

What is the indication for corneal transplantation when the cornea is likely to break open?

What is the primary function of immune privilege?

The anterior chamber is not immune privileged.

What is an allograft?

The eye is protected from immune reactions that are potentially dangerous in the _______________________ chamber.

Which of the following is NOT an example of an immune privileged site?

Corneal graft rejection is a major concern in eye transplantation.

Match the following immune privileged sites with their characteristics:

What is the purpose of immune privilege in the eye?

What is the primary mechanism of direct pathway in corneal graft rejection?

Corneal graft rejection is always symptomatic.

What are the two mechanisms of corneal graft rejection?

The indirect pathway of corneal graft rejection leads to ______ hypersensitivity.

Match the following risk factors with their corresponding descriptions:

What is the primary site of antigen processing in corneal graft rejection?

ABO blood type incompatibility is a confirmed risk factor for corneal graft rejection.

What is the common complaint associated with corneal graft rejection?

Study Notes

Mechanisms of Immune Privilege

Anterior Chamber-Associated Immune Deviation (ACAID)

Corneal Graft Rejection

Why Immune Privilege?

Corneal Transplantation

Why is Corneal Transplantation Successful?

Risk Factors for Corneal Graft Rejection

Studying That Suits You

More Quizzes Like This

Ocular physiology

OPT 2064 Ocular Biology: Retina Histology Overview

Canal of Hannover Eye Ocular Anatomy Quiz and Flashcards

Ocular Manifestations of Autoimmune Diseases