24 Questions
Which of the following can induce loss of self-tolerance?
Physical agents as x-rays or UV light
What is the mechanism by which Streptococcus pyogenes can trigger rheumatic fever?
Molecular mimicry
What type of immune response is responsible for autoimmune hemolytic anemia?
Type II or cytolytic reaction
Which of the following is NOT a mechanism of peripheral regulation?
Antibody-dependent cellular cytotoxicity
What is the role of antibiotic therapy in strep throat?
To prevent development of rheumatic heart disease
Which of the following is an example of autoantibody-mediated autoimmune disease?
Autoimmune hemolytic anemia
What is the primary mechanism of central tolerance mechanisms?
Clonal deletion
Which of the following is NOT a cause of tissue damage in autoimmune diseases?
Type I hypersensitivity reaction
What is the consequence of immune complexes of a certain size not being removed by mononuclear phagocytes?
Vasculitis and inflammation
What is the mechanism by which the immune system normally removes immune complexes?
Removal by mononuclear phagocytes in the liver and spleen
What is the term for the loss of tolerance to self-antigens, leading to an immune response against the body's own tissues?
Autoimmunity
What is the term for the process by which the immune system fails to distinguish between self and non-self, leading to an immune response against the body's own tissues?
Loss of tolerance
What is the term for the process by which the immune system recognizes and responds to antigens that are similar in structure to self-antigens?
Molecular mimicry
What is the term for the mechanisms that prevent the activation of autoreactive T cells in the periphery?
Peripheral regulation
What is the term for the process by which immature T cells that recognize self-antigens are eliminated or inactivated in the thymus?
Central tolerance
What is the term for the antibodies produced against the body's own tissues in autoimmune diseases?
Autoantibodies
What is the primary mechanism of central tolerance?
Central elimination or inhibition of self-reactive clones
Which of the following statements about self-tolerance is false?
It is a natural response to foreign antigens
What is the consequence of the reappearance of self-reactive clones during adult life?
Autoimmune diseases
Which of the following organs is responsible for central tolerance in T cells?
Thymus
What is the term for the absence of specific immune response to a particular antigen?
Unresponsiveness
Which of the following is an example of specifically induced tolerance?
Induction of immune tolerance in therapy of allergic conditions
What is the term for the mechanism by which the immune system distinguishes between self and non-self?
Self-tolerance
Which of the following is a consequence of loss of self-tolerance?
Autoimmune diseases
Study Notes
Immunology
- Physical agents like x-rays or UV light, chemicals or drugs, and viral infections can trigger immune responses.
- Exposure to microbial antigens that cross-react with self-antigens can lead to autoimmune diseases, such as rheumatic fever caused by Streptococcus pyogenes.
Rheumatic Fever and Rheumatic Heart Disease
- β-Haemolytic strains of Streptococcus pyogenes can cause strep throat, which requires antibiotic therapy to prevent the development of rheumatic heart disease.
- The M protein on the surface of Streptococcus pyogenes has structural similarity with molecules found in heart valves, joints, and kidneys.
Autoimmune Diseases
- Autoimmune diseases occur due to hypersensitivity reactions, except type I, and can cause tissue damage.
- Humoral hypersensitivity immune responses, such as type II or cytolytic reactions, can lead to autoimmune hemolytic anemia.
Hypersensitivity Reactions
- Type III hypersensitivity reactions involve the formation of immune complexes (Ag-Ab) that can deposit in small blood vessels, leading to inflammation (vasculitis).
- Immune complexes can cause harm, particularly in persistent infections, inhalation of antigenic material, or autoimmune diseases.
Immunological Tolerance or Self-Tolerance
- Immunological tolerance refers to controlled specific immunologic unresponsiveness to an antigen, which can be naturally acquired or specifically induced.
- Naturally acquired tolerance occurs during fetal development and involves unresponsiveness to one's own antigens, while specifically induced tolerance is used in therapy for allergic conditions and allograft rejections.
Self-Tolerance Mechanisms
- Central tolerance occurs in central lymphoid organs, such as the bone marrow and thymus, where self-reactive lymphocytes are eliminated or inhibited.
- The elimination of self-reactive clones during fetal development prevents autoimmune diseases, and their reappearance in adulthood can lead to autoimmune diseases.
This quiz covers various topics in microbiology and immunology, including physical and chemical agents, microbial antigens, and molecular mimicry. It tests your knowledge of microorganisms, immune responses, and related diseases.
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