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Questions and Answers
Which immunoglobulins are primarily involved in Type II hypersensitivity reactions?
Which immunoglobulins are primarily involved in Type II hypersensitivity reactions?
What is a characteristic clinical manifestation of Type III hypersensitivity reactions?
What is a characteristic clinical manifestation of Type III hypersensitivity reactions?
Which type of hypersensitivity is primarily cell-mediated?
Which type of hypersensitivity is primarily cell-mediated?
In which phase of Allergic Contact Dermatitis does sensitization occur?
In which phase of Allergic Contact Dermatitis does sensitization occur?
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What defines a graft versus host disease (GVHD)?
What defines a graft versus host disease (GVHD)?
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What type of transplantation involves tissues from genetically identical individuals?
What type of transplantation involves tissues from genetically identical individuals?
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Which type of rejection is primarily mediated by antibodies?
Which type of rejection is primarily mediated by antibodies?
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In transplantation immunopathology, what is an allograft?
In transplantation immunopathology, what is an allograft?
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What characterizes the initial phase response of a Type I hypersensitivity reaction?
What characterizes the initial phase response of a Type I hypersensitivity reaction?
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Which cells primarily mediate Type I hypersensitivity reactions?
Which cells primarily mediate Type I hypersensitivity reactions?
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What can potentially trigger anaphylactic reactions?
What can potentially trigger anaphylactic reactions?
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Which conditions are typically associated with atopic allergic conditions?
Which conditions are typically associated with atopic allergic conditions?
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What is a common symptom of allergic rhinitis?
What is a common symptom of allergic rhinitis?
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What is true regarding the secondary phase of a Type I hypersensitivity reaction?
What is true regarding the secondary phase of a Type I hypersensitivity reaction?
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Which of the following is NOT a common manifestation of food allergies?
Which of the following is NOT a common manifestation of food allergies?
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What is the primary use of preloaded epinephrine syringes in allergic reactions?
What is the primary use of preloaded epinephrine syringes in allergic reactions?
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What is the primary function of a properly functioning immune system?
What is the primary function of a properly functioning immune system?
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Which of the following is a characteristic of the adaptive immune system?
Which of the following is a characteristic of the adaptive immune system?
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What type of immunodeficiency is characterized by the absence or dysfunction of one or more components of the immune system?
What type of immunodeficiency is characterized by the absence or dysfunction of one or more components of the immune system?
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What is the treatment of choice for most primary immunodeficiency disorders?
What is the treatment of choice for most primary immunodeficiency disorders?
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What defines hypersensitivity in the context of the immune system?
What defines hypersensitivity in the context of the immune system?
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Which type of disorder involves the malfunction of both T-cells and B-cells within the immune system?
Which type of disorder involves the malfunction of both T-cells and B-cells within the immune system?
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Which of the following best describes the immediate response of the innate immune system?
Which of the following best describes the immediate response of the innate immune system?
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Which immunodeficiency disorder is primarily caused by environmental factors or infections?
Which immunodeficiency disorder is primarily caused by environmental factors or infections?
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Study Notes
Disorders of the Immune Response
- The immune system is a complex system designed to protect the body from foreign substances, microorganisms, and toxins.
- It plays a crucial role in inflammation and wound healing, and also protects against the growth of cancerous cells.
- The immune system can become inefficient or overactive, leading to various disorders.
- These disorders can be debilitating or life-threatening.
Types of Immune Disorders
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Immunodeficiency disorders: These occur when the immune system is weakened.
- There are two categories: primary and secondary.
- Primary immunodeficiencies are present at birth.
- Secondary immunodeficiencies develop later in life, often due to other factors.
- Allergic or hypersensitivity reactions: These occur when the immune system overreacts to harmless substances such as pollen or dust.
- Transplant rejection: The body's immune system recognizes a transplanted organ as foreign and attacks it.
- Autoimmune disorders: The immune system mistakenly attacks the body's own tissues.
Immune System Components
- The immune system is composed of two interconnected systems:
- Innate immune system: The body's first line of defense against infections, acting quickly.
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Adaptive immune system: This system provides a more specific response, remembering past invaders to fight more effectively.
- Humoral immunity (B-cell mediated): This involves the production of antibodies by B cells.
- Cell-mediated immunity (T-cell mediated): This involves the activation of T cells to directly attack infected cells.
Immunodeficiency Disorders (Details)
- Immunodeficiencies can result in increased susceptibility to infections.
- Types of primary immunodeficiencies include:
- Humoral (B-cell) Immunodeficiencies
- T-Cell Immunodeficiency
- Combined T-Cell and B-Cell immunodeficiency
- Complement System Disorders
- Phagocytosis disorders
Stem Cell Transplantation
- In many primary immunodeficiency disorders, stem cell transplantation from an HLA-compatible sibling is the treatment of choice.
- This procedure effectively restores the immune system in approximately 90% of patients, improving survival.
Hypersensitivity Disorders
- The immune system has a protective role in fighting off infection and foreign substances, but an inappropriate response can lead to serious damage.
- Hypersensitivity disorders involve an excessive immune response that causes tissue damage.
- These disorders are usually classified in different types based on the mechanisms involved in the response.
Type I Hypersensitivity Disorders (details)
- IgE-mediated reactions usually occur rapidly after exposure to an allergen.
- Key cells involved in these reactions are Type 2 helper T cells and Mast cells/Basophils.
- The response is split into two distinct phases:
- Initial phase, involving vasodilation, vascular leakage, causing inflammation, and smooth muscle contraction.
- Secondary/late phase, involving chronic inflammation, infiltration of inflammatory cells, and tissue destruction.
Anaphylactic Reactions
- Anaphylaxis is a widespread, life-threatening hypersensitivity reaction involving the entire body.
- Symptoms range from mild to severe and are characterized by a massive release of histamine into the bloodstream.
- The response is graded on a scale of I to IV.
- Pre-loaded epinephrine syringes and patient education on their use are crucial in managing anaphylaxis.
Atopic Reactions
- Local hypersensitivity reactions that usually manifest at the site of exposure to an allergen.
- Common symptoms involve urticaria (hives), allergic rhinitis, atopic dermatitis, and bronchial asthma.
- People experiencing atopic reactions often have high levels of IgE specific to allergens.
Allergic Rhinitis
- Allergic rhinitis affects the upper respiratory tract.
- It involves an inflammatory response resulting in symptoms such as rhinorrhea, nasal congestion, sneezing, nasal itching, and watery eyes.
- May be perennial (constant) or seasonal in nature, and specific triggers should be considered with patient care.
Food Allergies
- Food allergies are common in many areas of the world.
- They occur when specific food proteins (allergens) trigger an immune response.
- The reaction arises when food allergens contact IgE antibodies in the intestinal mucosa, resulting in a severe immune reaction.
- Peanuts, tree nuts, and shellfish are frequent triggers.
- Anaphylactic reactions to food allergens are common and require urgent medical intervention.
Type II Hypersensitivity Disorders
- Antibody-mediated hypersensitivity reactions target antigens on specific host cell surfaces, initiating an immune response, potentially resulting in destruction of the host cells.
- This could be intrinsic (part of host cell) or extrinsic (introduced via foreign exposure).
Type III Hypersensitivity Disorders
- These are immune complex-mediated hypersensitivity disorders.
- They occur when antigen–antibody complexes are formed in the blood and later deposited in blood vessels or tissues.
Type IV Hypersensitivity Disorders
- These are mediated by cell-mediated immunity, with no direct antibody involvement, and it develops more slowly than immediate hypersensitivity reactions.
- Examples of Type IV hypersensitivity include allergic contact dermatitis.
Allergic Contact Dermatitis
- A reaction of the skin caused by contact with an allergenic agent.
- The reaction involves an inflammatory response in two phases: sensitization and elicitation.
- Localized rash is often observed where the allergic contact occurred.
Transplantation Immunopathology
- Grafts are categorized as allografts (between different individuals), autografts (self-to-self), syngeneic (grafts between genetically identical individuals), and allogenic (donors and recipients have different genetic backgrounds).
Transplantation Rejection
- Transplant rejection involves a complex immune response where the recipient's immune system recognizes the graft as foreign and attacks it.
- Three types of rejection are present: cell-mediated, antibody-mediated, and chronic rejection.
Graft-versus-Host Disease (GVHD)
- GVHD is a potentially life-threatening complication, primarily after allogeneic stem cell transplantation.
- It occurs when immune cells from the donor (graft) attack the recipient's tissues.
- GVHD has three fundamental requirements for development: (1) the graft must contain functional immune cells; (2) the recipient must express antigens different from those on donor cells; (3) the recipient's immune system must be weakened to allow the donor cells to proliferate and attack recipient tissues.
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Description
This quiz explores the complexities of the immune system, focusing on various disorders that can arise from its dysfunction. Learn about immunodeficiency disorders, allergic reactions, and transplant rejections. Understand how these conditions can affect health and well-being.
