129 Questions
Which type of hypersensitivity is not mediated by antibodies?
Type IV
Which cells are responsible for much of the tissue damage in Hypersensitivity type IV?
activated Macrophages by which are activated by cytokines by TH1 cells
This type of hypersensitivity involves the introduction of antigen into the skin and phagocytosis by local antigen presenting cells (APCs).
type IV hypersensitivities
Which subcategory of type IV hypersensitivity is associated with chronic asthma and allergic rhinitis? (*hint there are 4 subcategories)
CD4 TH2-mediated reactions
What is the first step in CD8 CTL-mediated reactions(associated with tissue transplant rejection and contact dermatitis)? also is a subcategory of hypersensitivities IV ( 3 sub cat)
APC process and presentation of antigen with MHC I to naïve CD8 T cells
Which cells are targeted and induced to undergo apoptosis in CD8 CTL-mediated reactions?
Cells presenting the same antigen with MHC I
What is an example of TH1-mediated hypersensitivity?
examples of this are observed in tuberculin the Mantoux skin test and contact dermatitis, such as occurs in latex allergy reactions.
In this subcategory of type IV Hypersensitivities, the soluble antigen is first inhaled, resulting in eosinophil recruitment and activation with the release of cytokines and inflammatory mediators.
CD4 TH2
What is the role of activated TH1 cells in CD8 CTL-mediated reactions?
Enhancement of CTL activation
What subcategory of hypersensitivities type IV is also known as delayed-type hypersensitivities
CD4-TH1
What is an example of CD8 CTL-mediated hypersensitivity?
Tissue transplant rejection
What is the role of antigen presenting cells in CD8 CTL-mediated reactions?
Presentation of antigen with MHC I to naïve CD8 T cells
Which type of hypersensitivity is not mediated by antibodies?
Type IV
Which cells are responsible for much of the tissue damage in delayed-type hypersensitivities?remember( Type IV hypersensitivity reactions are T-cell–mediated reactions)
Macrophages
What is the sensitization step in delayed-type hypersensitivities?
Introduction of antigen into the skin
Which subcategory of type IV hypersensitivity is associated with chronic asthma and allergic rhinitis?
CD4 TH2-mediated reactions
What is the first step in CD8 CTL-mediated reactions?
Presentation of antigen with MHC I to naïve CD8 T cells
Which cells are targeted and induced to undergo apoptosis in CD8 CTL-mediated reactions?
Cells presenting the same antigen with MHC I
What is an example of TH1-mediated hypersensitivity?
Tuberculin the Mantoux skin test
What type of cells are responsible for the release of cytokines and inflammatory mediators in CD4 TH2-mediated reactions?
Eosinophils
What is the role of activated TH1 cells in CD8 CTL-mediated reactions?
Enhancement of CTL activation
What is the second step in delayed-type hypersensitivities?
Introduction of antigen into the skin
What is an example of CD8 CTL-mediated hypersensitivity?
Tissue transplant rejection
What is the role of antigen presenting cells in CD8 CTL-mediated reactions?
Presentation of antigen with MHC I to naïve CD8 T cells
What is the main difference between type IV hypersensitivity and the other three types of hypersensitivity?
Type IV hypersensitivity involves the action of effector cells.
Which T-cell subtype is involved in delayed-type hypersensitivities (DTH)?
CD4 TH1 cells
What is the sensitization step in delayed-type hypersensitivities (DTH)?
Introduction of antigen into the skin and phagocytosis by local antigen presenting cells (APCs)
What is the effector mechanism in delayed-type hypersensitivities (DTH)?
Activation of macrophages
What is an example of TH1-mediated hypersensitivity?
Tuberculin the Mantoux skin test
What is the result of CD4 TH2-mediated reactions?
Chronic asthma or chronic allergic rhinitis
What is the result of CD8 cytotoxic T lymphocyte (CTL)-mediated reactions?
Tissue transplant rejection and contact dermatitis
What is the role of antigen presenting cells (APCs) in CD8 CTL-mediated reactions?
Process and present the antigen with MHC I to naïve CD8 T cells
What do activated CTLs target in CD8 CTL-mediated reactions?
Self cells that have absorbed the foreign antigen
What is the effector mechanism in CD8 CTL-mediated reactions?
Induction of granzyme-mediated apoptosis in cells presenting the same antigen with MHC I
What is the difference between CD4 TH1-mediated reactions and CD4 TH2-mediated reactions?
The type of antigen involved
What is the difference between CD8 CTL-mediated reactions and CD4 TH1-mediated reactions?
The T-cell subtype involved
What type of cells are involved in regulating Type IV hypersensitivities?
T cells
How many subcategories can Type IV hypersensitivities be organized into?
Three
Which T-cell subtype is responsible for much of the tissue damage in delayed-type hypersensitivities (DTH)?
CD4 TH1-mediated reactions
What condition is caused by CD4 TH2-mediated reactions?
Chronic asthma
What is the association between CD8 cytotoxic T lymphocyte (CTL)-mediated reactions and tissue transplant rejection?
CD8 CTL-mediated reactions cause tissue transplant rejection
What causes Hypersensitivity pneumonitis (HP)?
All of the above
What types of hypersensitivities are associated with pathology in Hypersensitivity pneumonitis (HP)?
Type III and Type IV
What diagnostic tests are required to diagnose Type I hypersensitivities?
Several diagnostic tests in addition to a well-documented patient history
What test can be performed to identify the antigens responsible for a type I reaction allergy?
Prick puncture skin test (PPST)
Why can Type III hypersensitivities often be misdiagnosed?
Because of their nonspecific inflammatory nature
What is the purpose of desensitization therapy?
To reduce the hypersensitivity reaction through repeated injections of allergens
How is emergency systemic anaphylaxis initially treated?
With an epinephrine injection
What is the treatment for Type III hypersensitivities?
Preventing further exposure to the antigen
Why can type III hypersensitivities often be misdiagnosed?
Because they have a nonspecific inflammatory nature
What is the initial treatment for emergency systemic anaphylaxis?
Epinephrine injection
What regulates type IV hypersensitivities?
T cells
What are CD8 cytotoxic T lymphocyte (CTL)-mediated reactions associated with?
Tissue transplant rejection and contact dermatitis
What is the effector mechanism involved in CD4 TH1-mediated reactions?
Release of cytokines and inflammatory mediators
What is the association between CD8 CTL-mediated reactions and tissue transplant rejection?
CD8 CTL-mediated reactions result in tissue transplant rejection
What is the cause of Hypersensitivity pneumonitis (HP)?
Inhalation of dust and endospores
What type of hypersensitivity can be due to both immune complexes and TH1 cells and macrophages?
Type III hypersensitivity
Why can type III hypersensitivities often be misdiagnosed?
They are too general in their inflammatory nature
What is desensitization therapy used for?
To reduce the hypersensitivity reaction through repeated injections of allergens
What is the treatment for type III hypersensitivities?
Preventing further exposure to the antigen
Which type of hypersensitivity is regulated by T cells and involves the action of effector cells?
Type IV hypersensitivity
What is the antigen presenting cell responsible for presenting antigens to T cells in delayed-type hypersensitivities?
Macrophages
What is the treatment for type III hypersensitivities?
Preventing further exposure to the antigen and the use of anti-inflammatory drugs
What is the diagnostic test used to identify antigens responsible for a type I reaction allergy?
Prick puncture skin test (PPST)
What is the emergency treatment for systemic anaphylaxis?
Epinephrine injection
What is the mechanism of CD8 CTL-mediated reactions?
Involves the action of effector cells
What is the mechanism of type IV hypersensitivities?
Regulated by T cells
What is the mechanism of CD4 TH2-mediated reactions?
Involves the action of effector cells
What is the effector mechanism of CD4 TH1-mediated reactions in type IV hypersensitivities?
Delayed-type hypersensitivity
What is the effector mechanism of CD4 TH2-mediated reactions in type IV hypersensitivities?
Antibody-mediated
Which of the following is NOT a cause of Hypersensitivity pneumonitis (HP)?
Bacteria
What type of hypersensitivity is associated with tissue transplant rejection and contact dermatitis?
Type IV
What is the initial treatment for emergency systemic anaphylaxis?
Epinephrine injection
What is the diagnostic test used to identify antigens responsible for a type I reaction allergy?
Prick puncture skin test
What is the effector mechanism of type III hypersensitivities?
Immune complex-mediated
What is the treatment for type III hypersensitivities?
Avoiding exposure to the antigen
What type of hypersensitivity requires several diagnostic tests in addition to a well-documented patient history for diagnosis?
Type I
What is the role of effector cells in type IV hypersensitivities?
Causing tissue damage
What is the name of the diagnostic test used for type IV hypersensitivities?
Intradermal test
What is the effector mechanism of CD8 CTL-mediated reactions in type IV hypersensitivities?
Cytotoxic T cell-mediated
What is hypersensitivity pneumonitis (HP)?
An allergic reaction to inhaled dust, endospores, bird feathers, bird droppings, molds, or chemicals that causes inflammation in the lungs
What are the two types of hypersensitivities that can cause pathology associated with HP?
Type III and Type IV
How is a type I hypersensitivity diagnosed?
Through several diagnostic tests and a well-documented patient history
What is desensitization therapy?
A therapy that reduces the hypersensitivity reaction through repeated injections of allergens
What is the initial treatment for emergency systemic anaphylaxis?
An epinephrine injection
What are CD4 TH1-mediated reactions responsible for?
Much of the tissue damage
What are CD4 TH2-mediated reactions associated with?
Chronic asthma or chronic allergic rhinitis
What are CD8 cytotoxic T lymphocyte (CTL)-mediated reactions associated with?
Tissue transplant rejection and contact dermatitis
What is Type IV hypersensitivity regulated by?
T cells
What are the three subcategories of Type IV hypersensitivities based on?
T-cell subtype, type of antigen, and the resulting effector mechanism
What is the treatment for Type III hypersensitivities?
Preventing further exposure to the antigen and the use of anti-inflammatory drugs
Why can Type III hypersensitivities often be misdiagnosed?
Because of their nonspecific inflammatory nature
Which type of hypersensitivity is associated with chronic asthma and allergic rhinitis?
Type I hypersensitivity
What is the pathology associated with Hypersensitivity pneumonitis (HP)?
Both type III and type IV hypersensitivities
What is the treatment for type III hypersensitivities?
Preventing further exposure to the antigen and the use of anti-inflammatory drugs
What is the initial treatment for emergency systemic anaphylaxis?
Epinephrine injection
What is the diagnostic test used to identify the antigens responsible for a type I reaction allergy?
Both PPST and intradermal test
Which subcategories can type IV hypersensitivities be organized into?
Three subcategories
What is the role of CD8 cytotoxic T lymphocytes in tissue transplant rejection?
Recognizing and killing cells of the transplanted tissue
What is the cause of Hypersensitivity pneumonitis (HP)?
Allergic reaction to inhaled dust, endospores, bird feathers, bird droppings, molds, or chemicals
What is the mechanism of type IV hypersensitivities?
Regulated by T cells and involve the action of effector cells
What is desensitization therapy used for?
Reducing the hypersensitivity reaction through repeated injections of allergens
What is the mechanism of CD4 TH1-mediated reactions?
Responsible for much of the tissue damage
What is the diagnostic requirement for type I hypersensitivities?
Patient history and several diagnostic tests
What is the mechanism of Type IV hypersensitivities?
Regulated by T cells and involve the action of effector cells
What are the three subcategories of Type IV hypersensitivities based on?
T-cell subtype, type of antigen, and the resulting effector mechanism
What are CD4 TH1-mediated reactions responsible for?
Much of the tissue damage
What do CD4 TH2-mediated reactions result in?
Chronic asthma or chronic allergic rhinitis
What are CD8 cytotoxic T lymphocyte (CTL)-mediated reactions associated with?
Tissue transplant rejection and contact dermatitis
What causes Hypersensitivity pneumonitis (HP)?
Inflammation due to an allergic reaction to inhaled dust
What are the two types of hypersensitivities associated with Hypersensitivity pneumonitis (HP)?
Type III and Type IV
What diagnostic tests are required for the diagnosis of Type I hypersensitivities?
Several diagnostic tests in addition to a well-documented patient history
What test can be performed to identify the antigens responsible for a Type I reaction allergy?
Prick puncture skin test (PPST)
Why are Type III hypersensitivities often misdiagnosed?
Due to their nonspecific inflammatory nature
What is desensitization therapy used for?
To reduce the hypersensitivity reaction through repeated injections of allergens
How is emergency systemic anaphylaxis initially treated?
With an epinephrine injection
What is the treatment for Type III hypersensitivities?
Preventing further exposure to the antigen and the use of anti-inflammatory drugs
What is the mechanism of Type IV hypersensitivities?
Regulated by T cells and involve the action of effector cells
Which subcategories can Type IV hypersensitivities be organized into?
Three subcategories
What are CD4 TH1-mediated reactions responsible for?
Tissue damage
What is the result of CD4 TH2-mediated reactions?
Chronic asthma
What are CD8 cytotoxic T lymphocyte (CTL)-mediated reactions associated with?
Tissue transplant rejection
What causes Hypersensitivity pneumonitis (HP)?
Inhalation of spores
What types of hypersensitivities can cause pathology associated with HP?
Both type III and type IV
What diagnostic tests are required for the diagnosis of type I hypersensitivities?
Patient history and several diagnostic tests
What tests can be performed to identify the antigens responsible for a type I reaction allergy?
Prick puncture skin test (PPST)
Why are type III hypersensitivities often misdiagnosed?
Because they are not specific in nature
What is the purpose of desensitization therapy?
To reduce the hypersensitivity reaction through repeated injections of allergens
What is the initial treatment for emergency systemic anaphylaxis?
Epinephrine injection
Study Notes
Understanding Hypersensitivities: Types, Diagnosis, and Treatment
- Type IV hypersensitivities are regulated by T cells and involve the action of effector cells.
- Type IV hypersensitivities can be organized into three subcategories based on T-cell subtype, type of antigen, and the resulting effector mechanism.
- CD4 TH1-mediated reactions are described as delayed-type hypersensitivities (DTH) and are responsible for much of the tissue damage.
- CD4 TH2-mediated reactions result in chronic asthma or chronic allergic rhinitis.
- CD8 cytotoxic T lymphocyte (CTL)-mediated reactions are associated with tissue transplant rejection and contact dermatitis.
- Hypersensitivity pneumonitis (HP) occurs when the lungs become inflamed due to an allergic reaction to inhaled dust, endospores, bird feathers, bird droppings, molds, or chemicals.
- Pathology associated with HP can be due to both type III (mediated by immune complexes) and type IV (mediated by TH1 cells and macrophages) hypersensitivities.
- Diagnosis of type I hypersensitivities requires several diagnostic tests in addition to a well-documented patient history.
- Prick puncture skin test (PPST) or an intradermal test can be performed to identify the antigens responsible for a type I reaction allergy.
- Type III hypersensitivities can often be misdiagnosed because of their nonspecific inflammatory nature.
- Desensitization therapy can be used to reduce the hypersensitivity reaction through repeated injections of allergens.
- Emergency systemic anaphylaxis is treated initially with an epinephrine injection, which can counteract the drop in blood pressure.
- Treatment of type III hypersensitivities includes preventing further exposure to the antigen and the use of anti-inflammatory drugs.
Understanding Hypersensitivities: Types, Diagnosis, and Treatment
- Type IV hypersensitivities are regulated by T cells and involve the action of effector cells.
- Type IV hypersensitivities can be organized into three subcategories based on T-cell subtype, type of antigen, and the resulting effector mechanism.
- CD4 TH1-mediated reactions are described as delayed-type hypersensitivities (DTH) and are responsible for much of the tissue damage.
- CD4 TH2-mediated reactions result in chronic asthma or chronic allergic rhinitis.
- CD8 cytotoxic T lymphocyte (CTL)-mediated reactions are associated with tissue transplant rejection and contact dermatitis.
- Hypersensitivity pneumonitis (HP) occurs when the lungs become inflamed due to an allergic reaction to inhaled dust, endospores, bird feathers, bird droppings, molds, or chemicals.
- Pathology associated with HP can be due to both type III (mediated by immune complexes) and type IV (mediated by TH1 cells and macrophages) hypersensitivities.
- Diagnosis of type I hypersensitivities requires several diagnostic tests in addition to a well-documented patient history.
- Prick puncture skin test (PPST) or an intradermal test can be performed to identify the antigens responsible for a type I reaction allergy.
- Type III hypersensitivities can often be misdiagnosed because of their nonspecific inflammatory nature.
- Desensitization therapy can be used to reduce the hypersensitivity reaction through repeated injections of allergens.
- Emergency systemic anaphylaxis is treated initially with an epinephrine injection, which can counteract the drop in blood pressure.
- Treatment of type III hypersensitivities includes preventing further exposure to the antigen and the use of anti-inflammatory drugs.
Understanding Hypersensitivities: Types, Diagnosis, and Treatment
- Type IV hypersensitivities are regulated by T cells and involve the action of effector cells.
- Type IV hypersensitivities can be organized into three subcategories based on T-cell subtype, type of antigen, and the resulting effector mechanism.
- CD4 TH1-mediated reactions are described as delayed-type hypersensitivities (DTH) and are responsible for much of the tissue damage.
- CD4 TH2-mediated reactions result in chronic asthma or chronic allergic rhinitis.
- CD8 cytotoxic T lymphocyte (CTL)-mediated reactions are associated with tissue transplant rejection and contact dermatitis.
- Hypersensitivity pneumonitis (HP) occurs when the lungs become inflamed due to an allergic reaction to inhaled dust, endospores, bird feathers, bird droppings, molds, or chemicals.
- Pathology associated with HP can be due to both type III (mediated by immune complexes) and type IV (mediated by TH1 cells and macrophages) hypersensitivities.
- Diagnosis of type I hypersensitivities requires several diagnostic tests in addition to a well-documented patient history.
- Prick puncture skin test (PPST) or an intradermal test can be performed to identify the antigens responsible for a type I reaction allergy.
- Type III hypersensitivities can often be misdiagnosed because of their nonspecific inflammatory nature.
- Desensitization therapy can be used to reduce the hypersensitivity reaction through repeated injections of allergens.
- Emergency systemic anaphylaxis is treated initially with an epinephrine injection, which can counteract the drop in blood pressure.
- Treatment of type III hypersensitivities includes preventing further exposure to the antigen and the use of anti-inflammatory drugs.
Test your knowledge of Type IV Hypersensitivities with this quiz! Learn about the different subcategories of Type IV hypersensitivities and the mechanisms behind them. Challenge yourself with questions on T-cell subtypes, antigen types, and effector mechanisms. Perfect for medical and immunology students or anyone interested in understanding this complex immune response.
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