Nokea
What is the mechanism of tissue damage in Type II hypersensitivity?
- A. Immune complex deposition
- B. Antibody binding to cell surface antigens, triggering complement activation or phagocytosis
- C. Mast cell degranulation
- D. T cell-mediated cytotoxicity
Correct Answer: B
Rationale: The correct answer is B: Antibody binding to cell surface antigens, triggering complement activation or phagocytosis. In Type II hypersensitivity, antibodies bind to antigens on host cells, leading to complement activation or phagocytosis by immune cells. This results in cell damage or destruction. Immune complex deposition (A) is more characteristic of Type III hypersensitivity. Mast cell degranulation (C) is seen in Type I hypersensitivity. T cell-mediated cytotoxicity (D) is associated with Type IV hypersensitivity, not Type II. Therefore, choice B is the most accurate mechanism of tissue damage in Type II hypersensitivity.
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The class of an immunoglobulin
- A. is determined by Class I and Class II major histocompatibility complex proteins
- B. is determined by the carbohydrate attached to the light chain is
- C. determined by the antigen
- D. is determined by the heavy chain type
Correct Answer: D
Rationale: The correct answer is D because the class of an immunoglobulin is determined by the type of heavy chain it possesses. There are five main classes of immunoglobulins (IgG, IgA, IgM, IgD, IgE) which are defined by the heavy chain constant region. Different heavy chain types result in different effector functions and biological properties. Choices A, B, and C are incorrect because the class of an immunoglobulin is not determined by Class I and Class II major histocompatibility complex proteins, carbohydrate attached to the light chain, or the antigen. These factors may influence the function or specificity of the antibody, but they do not determine its class.
All of the following are true about antibodies, EXCEPT which one?
- A. They fix complement.
- B. They occur on the surface of B-lymphocyte
- C. They predominate the primary immune response to antigen.
- D. have a single, defined amino acid sequence due to variability.
Correct Answer: D
Rationale: The correct answer is D because antibodies do not have a single, defined amino acid sequence due to variability in their structure. This variability is a result of somatic recombination and hypermutation.
A: Antibodies can fix complement, leading to the destruction of pathogens.
B: Antibodies are produced by B-lymphocytes and can occur on their surface as B-cell receptors.
C: Antibodies predominate the secondary immune response, not the primary response, as memory B-cells are generated during the primary response for a quicker and more robust secondary response.
Which of the following is NOT a property of CD8+ T cells?
- A. They typically differentiate into cytotoxic T cells (Tc)
- B. They always recognize peptide antigen in association with an MHC molecule
- C. They are important in defense against intracellular pathogens
- D. They are the cell responsible for antibody-dependent cell-mediated cytotoxicity
Correct Answer: D
Rationale: The correct answer is D because CD8+ T cells are not responsible for antibody-dependent cell-mediated cytotoxicity. A is correct as CD8+ T cells differentiate into cytotoxic T cells. B is correct as CD8+ T cells recognize peptide antigens with MHC molecules. C is correct as CD8+ T cells are vital in defense against intracellular pathogens. D is incorrect as CD8+ T cells do not mediate cell cytotoxicity through antibodies.
Which scientist is credited with identifying Toll-like receptors (TLRs) in innate immunity?
- A. Paul Ehrlich
- B. Jules Hoffman
- C. Edward Jenner
- D. Louis Pasteur
Correct Answer: B
Rationale: The correct answer is B: Jules Hoffman. He is credited with identifying Toll-like receptors (TLRs) in innate immunity. Hoffman's research provided crucial insights into how the immune system recognizes pathogens and triggers immune responses. Paul Ehrlich is known for his work on antibodies, Edward Jenner for developing the smallpox vaccine, and Louis Pasteur for his contributions to germ theory and vaccination. However, none of them are specifically associated with the discovery of Toll-like receptors in innate immunity.
What percent of clients with chronic fatigue syndrome (CFS) will experience hypotension during a tilt table test,which can eventually be diagnostic for these clients?
- A. 60%
- B. 96%
- C. 80%
- D. 20%
Correct Answer: B
Rationale: Approximately 96% of clients with CFS experience hypotension during a tilt table test which helps in diagnosing the condition.