Immunology and Allergic Reactions

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Questions and Answers

What is the most common allergic response of the eye?

Allergic conjunctivitis (correct)

Atopic dermatitis

Food allergy

Asthma

Anaphylactic shock is a mild allergic reaction.

False

What is the characteristic of perennial allergic conjunctivitis?

Atopic patient

A family history of allergic reactions may include ______________.

other allergic reactions Signup and view all the answers

Match the following allergic reactions with their symptoms:

Urticaria = Large, itchy red swellings all over body Anaphylactic shock = May be fatal Allergic conjunctivitis = Itching, tearing, and redness Atopic dermatitis = Dry, scaly skin Signup and view all the answers

Allergic rhinitis is also known as hay fever.

True Signup and view all the answers

What is the characteristic of long-standing allergic conjunctivitis?

Permanent changes Signup and view all the answers

In allergic conjunctivitis, the conjunctiva may appear ______________.

oedematous Signup and view all the answers

What is a crucial symptom that would make the diagnosis of allergic conjunctivitis likely?

Itching Signup and view all the answers

True or False: Myasthenia Gravis is an example of Type I hypersensitivity reaction.

False Signup and view all the answers

What is the primary function of Type II hypersensitivity?

Elimination of unwanted organisms and removal of potential malignant cells. Signup and view all the answers

In Type II hypersensitivity, specific antibodies bind to ____________________ antigens.

cell surface Signup and view all the answers

Match the following hypersensitivity reactions with their respective mechanisms:

Type I hypersensitivity = Allergic reactions Type II hypersensitivity = Antibody-dependent cell-mediated cytotoxicity Myasthenia Gravis = Autoimmune disorder Signup and view all the answers

True or False: Corticosteroids are used to treat allergic conjunctivitis.

True Signup and view all the answers

What is the differential diagnosis for allergic conjunctivitis?

Bacterial conjunctivitis and viral conjunctivitis. Signup and view all the answers

What is the primary goal of management in allergic conjunctivitis?

Avoid allergen Signup and view all the answers

What is the result of antibodies against receptors of the nerves?

Fatigue of the nerve and paralysis of the muscle Signup and view all the answers

Antibodies formed against foreign red cells lead to destruction of red cells in the spleen.

False Signup and view all the answers

What is the mechanism of destruction of red cells in the spleen?

Destruction of red cells in the spleen by macrophages Signup and view all the answers

Type III hypersensitivity is also known as _____________ mediated hypersensitivity.

immune-complex Signup and view all the answers

What is the result of rapid influx of antigen overwhelming the coping mechanisms?

Deposition of immune complexes on vessel walls/tissue Signup and view all the answers

Antibody reacts to a soluble antigen to form a network of antigen:antibody complexes.

True Signup and view all the answers

Match the following types of hypersensitivity with their descriptions:

Type III hypersensitivity = Deposition of immune complexes on vessel walls/tissue Incompatible transfusion = Destruction of red cells in the spleen by macrophages Signup and view all the answers

What is the management of antibody-directed against an antigen on the red cell surface?

Immunosuppression Signup and view all the answers

What is a characteristic of inflammation due to an allergic reaction?

Redness due to dilated vessels Signup and view all the answers

Dendritic cells in the cornea are responsible for antimicrobial activity against bacteria, fungi, and viruses.

False Signup and view all the answers

What is the function of Conjunctiva-Associated Lymphoid Tissue (CALT)?

CALT contains CD4+ and CD8+ T-cells, B-cells, and abundant IgA immunoglobulins, leading to a cell-mediated immune response. Signup and view all the answers

Keratocytes secrete _______________, which have antimicrobial activity against bacteria, fungi, and viruses.

defensins Signup and view all the answers

Match the following components of the eye with their functions:

Corneal nerves = Reflexive movements to protect the eye Keratocytes = Antigen-presenting cells Dendritic cells = Secrete defensins Complement = Acceleration of epithelial healing Signup and view all the answers

What is the function of the orbital skeletal structure?

To minimize potential trauma Signup and view all the answers

Tears play a role in the immune response.

True Signup and view all the answers

How can eye infections be classified?

According to the infectious organism involved or the affected structure within the eye Signup and view all the answers

Scleral immunology is characterized by the presence of dense fibrotic tissue and acid mucopolysaccharides.

True Signup and view all the answers

What is the role of physical barriers in ocular immunity?

To prevent pathogens from entering the eye Signup and view all the answers

What is the role of chemosis in an allergic reaction?

Chemosis, or swelling, is a characteristic of inflammation due to an allergic reaction. Signup and view all the answers

The _____________ tract is part of the ocular immune system.

uveal Signup and view all the answers

Match the following components of ocular immunity:

Cornea = Physical barrier against pathogens Conjunctiva = Mucous membrane that helps to flush out pathogens Tears = Contain enzymes that break down pathogens Signup and view all the answers

What is the role of the haematologist in ocular immunity?

To diagnose and treat blood disorders Signup and view all the answers

Immune dysfunction can lead to immunodeficiency.

True Signup and view all the answers

What is the role of MHC class I in ocular immunity?

To recognize and present antigens to T-cells Signup and view all the answers

What is the main function of the orbital skeletal structure in ocular immunity?

To minimize potential trauma Signup and view all the answers

Tears play a role in the immune response.

True Signup and view all the answers

What is the primary goal of management in allergic conjunctivitis?

To reduce symptoms and prevent complications Signup and view all the answers

The _____________ tract is part of the ocular immune system.

Uveal Signup and view all the answers

Match the following components of ocular immunity with their functions:

Conjunctiva-Associated Lymphoid Tissue (CALT) = Responsible for tear production Cornea = Responsible for antimicrobial activity Tears = Provides physical barrier function Orbital skeletal structure = Regulates chemosis in allergic reactions Signup and view all the answers

What is a characteristic of allergic conjunctivitis?

Inflammation due to an allergic reaction Signup and view all the answers

Immune dysfunction can lead to immunodeficiency.

True Signup and view all the answers

What is the role of the haematologist in ocular immunity?

To diagnose and manage immune-related disorders Signup and view all the answers

What is the result of antibodies against receptors of the nerves?

Fatigue of the nerve and paralysis of the muscle Signup and view all the answers

Type III hypersensitivity is also known as immune-complex mediated hypersensitivity.

True Signup and view all the answers

What is the mechanism of destruction of red cells in the spleen?

Destruction of red cells by macrophages Signup and view all the answers

Antibodies formed against foreign red cells lead to destruction of red cells in the _______________.

spleen Signup and view all the answers

What is the result of a rapid influx of antigen overwhelming the coping mechanisms?

Local or systemic effects Signup and view all the answers

Match the following hypersensitivity reactions with their respective mechanisms:

Type II = Antibody directed against an antigen on the red cell surface Type III = Deposition of immune complexes on vessel walls Type I = Anaphylaxis Type IV = Cell-mediated immune response Signup and view all the answers

Immune complexes are formed in Type II hypersensitivity.

False Signup and view all the answers

What is the management of antibody-directed against an antigen on the red cell surface?

Immunosuppression Signup and view all the answers

What is the characteristic of inflammation due to an allergic reaction?

Redness due to dilated vessels Signup and view all the answers

Dendritic cells in the cornea are responsible for antimicrobial activity against bacteria, fungi, and viruses.

False Signup and view all the answers

What is the function of Conjunctiva-Associated Lymphoid Tissue (CALT)?

Antigen-presenting cells, leading to cell-mediated immune response Signup and view all the answers

Keratocytes secrete ___________________, which have antimicrobial activity against bacteria, fungi, and viruses.

defensins Signup and view all the answers

Match the following components of the eye with their functions:

Corneal nerves = Reflexive movements to protect the eye Keratocytes = Secrete defensins Dendritic cells = Antigen-presenting cells Conjunctiva-Associated Lymphoid Tissue (CALT) = Accelerate epithelial healing Signup and view all the answers

How can eye infections be classified?

Both a and b Signup and view all the answers

Scleral immunology is characterized by the presence of dense fibrotic tissue and acid mucopolysaccharides.

True Signup and view all the answers

What is the result of chemosis in an allergic reaction?

Swelling Signup and view all the answers

What is the severe form of an allergic reaction that can be fatal?

Anaphylactic shock Signup and view all the answers

Allergic conjunctivitis is a Type II hypersensitivity reaction.

False Signup and view all the answers

What is the crucial symptom that would make the diagnosis of allergic conjunctivitis likely?

Itching Signup and view all the answers

Type II hypersensitivity is also known as antibody-mediated hypersensitivity.

True Signup and view all the answers

What is the common name for allergic rhinitis?

Hay fever Signup and view all the answers

What is the primary function of Type II hypersensitivity?

Elimination of unwanted organisms and removal of potential malignant cells Signup and view all the answers

Atopic dermatitis is also known as _______________.

Eczema Signup and view all the answers

Match the following allergic reactions with their symptoms:

Urticaria = Large, itchy red swellings all over the body Anaphylactic shock = May be fatal Allergic rhinitis = Runny nose, sneezing, and itchy eyes Atopic dermatitis = Dry, itchy, and scaly skin Signup and view all the answers

In Type II hypersensitivity, specific antibodies bind to _______________ antigens.

cell surface Signup and view all the answers

What is the differential diagnosis for allergic conjunctivitis?

Bacterial conjunctivitis and Viral conjunctivitis Signup and view all the answers

What is the primary symptom of allergic conjunctivitis?

All of the above Signup and view all the answers

What is the primary goal of management in allergic conjunctivitis?

To reduce symptoms and prevent long-term complications Signup and view all the answers

Corticosteroids are used to treat allergic conjunctivitis.

True Signup and view all the answers

Food allergy can cause anaphylactic shock.

True Signup and view all the answers

Match the following hypersensitivity reactions with their mechanisms:

Type II hypersensitivity = Antibody-dependent cell-mediated cytotoxicity (ADCC) Type I hypersensitivity = Antibody-mediated reaction Type III hypersensitivity = Complement activation Signup and view all the answers

What is the primary goal of management in allergic conjunctivitis?

Avoid allergen Signup and view all the answers

Study Notes

Type I Hypersensitivity

Allergic reactions: allergic rhinitis (hay fever), asthma, atopic dermatitis (eczema), and food allergy
Symptoms: vary, mild (urticaria), severe (anaphylactic shock)
Allergic conjunctivitis: most common allergic response of the eye
Clinical picture: symptoms (itching, tearing, foreign body sensation, redness, photophobia), signs (oedema, conjunctiva/eyelid, prominent blood vessels, atopic patients)

Type I Hypersensitivity and the Eye

Allergic conjunctivitis: differential diagnosis (bacterial, viral conjunctivitis), management (avoid allergen, topical treatment, antihistamines, mast cell stabilisers, corticosteroids)
Pathophysiology: destruction of red cell in spleen by macrophages, antibodies against receptors of the nerves, leads to "fatigue" of the nerve and paralysis of the muscle

Type II Hypersensitivity

Antibody-mediated hypersensitivity: specific antibodies bind to cell surface antigens (IgM and/or IgG)
Physiological functions: elimination of unwanted organisms, removal of potential malignant cells
Clinical examples: autoimmune haemolytic anaemia, myasthenia gravis
Antibody-dependent cell-mediated cytotoxicity (ADCC): complement activation, ADCC, and phagocytosis

Type III Hypersensitivity

Immune-complex mediated hypersensitivity: rapid influx of antigen overwhelms coping mechanisms
Deposition of immune complexes on vessel walls/tissue, leads to damage by complement or neutrophils
Local or systemic effects: local (farmers lung), systemic (certain autoimmune diseases, e.g. asthma, rhinitis)

Ocular Immunity

Physical barriers: orbital skeletal structure minimises potential trauma
Tears: play a role in ocular defence mechanisms
Conjunctival immune response: dendritic cells, keratocytes, corneal nerves
Uveal tract: dense fibrotic tissue, acid mucopolysaccharides

Acquired Immune Responses

Dendritic cells in the cornea: antigen-presenting cells, lead to cell-mediated immune response
Conjunctiva-Associated Lymphoid Tissue (CALT): contains CD4+ and CD8+ T-cells, B-cells, and abundant IgA immunoglobulins
Corneal nerves: reflexive movements to protect the eye, sensations of discomfort and pain### Features of Inflammation/Allergic Reaction
Redness occurs due to dilated vessels
Chemosis, or swelling, is a characteristic feature

Immune Response in the Cornea

Dendritic cells in the cornea act as antigen-presenting cells, leading to a cell-mediated immune response
Keratocytes secrete defensins, which have antimicrobial activity against bacteria, fungi, and viruses, and accelerate epithelial healing

Other Protective Measures

Corneal nerves trigger reflexive movements to protect the eye and transmit sensations of discomfort and pain
Conjunctiva-Associated Lymphoid Tissue (CALT) contains CD4+ and CD8+ T-cells, B-cells, and abundant IgA immunoglobulins

Complement System

Complement is concentrated in the peripheral cornea and can be activated through either the classical or alternate pathway

Scleral Immunology

The sclera is composed of dense fibrotic tissue and acid mucopolysaccharides

Ocular Infections

Ocular infections can be classified according to the infectious organism involved or the structure within the eye that is affected

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Description

Learn about the different types of allergic reactions, including allergic rhinitis, asthma, atopic dermatitis, and their varying symptoms. Test your knowledge of type I hypersensitivity and its effects on the body.