ATI LPN
Questions on Immune System Questions
Question 1 of 5
C3 is cleaved to form C3a and C3b by C3 convertase. C3b is involved in all of the following EXCEPT
Correct Answer: A
Rationale: The correct answer is A because C3b is not involved in altering vascular permeability. C3b plays a role in promoting phagocytosis by opsonizing pathogens, forming alternative-pathway C3 convertase for amplifying the complement cascade, and forming C5 convertase to initiate the terminal pathway. In contrast, altering vascular permeability is primarily mediated by other factors such as histamine and bradykinin. Therefore, C3b's involvement in altering vascular permeability is not supported by the functions it actually performs in the complement system.
Question 2 of 5
The BEST method to demonstrate IgG on the glomerular basement membrane in a kidney tissue section is the
Correct Answer: D
Rationale: The correct answer is D: indirect fluorescent-antibody test. This method is the best for demonstrating IgG on the glomerular basement membrane in kidney tissue. It involves applying a fluorescent-tagged anti-IgG antibody, which specifically binds to IgG on the tissue section, producing a visible fluorescent signal under a microscope. This technique allows for precise localization and visualization of IgG deposition. A: precipitin test and C: agglutination test are not suitable for detecting IgG specifically on tissue sections. B: complement fixation test is not commonly used for direct visualization of IgG in tissues. The indirect fluorescent-antibody test is the most sensitive and specific method for detecting IgG in tissue samples.
Question 3 of 5
Which one of the following is NOT true of the gene segments that combine to make up a heavy-chain gene?
Correct Answer: D
Rationale: The correct answer is D because the statement is false. Antigens do not preselect V and J segments for gene recombination. Instead, the process is random. V, D, and J segments do combine to encode the antigen-binding site, making choice C true. Choice A is true because there are many V region segments available for gene recombination. Choice B is also true as there are several J segments and several D segments available for recombination. Therefore, the correct answer is D because it inaccurately describes the process of gene segment recombination.
Question 4 of 5
Proteins from two samples of animal blood, A and B, were tested by the double-diffusion (Ouchterlony) test in agar against antibody to bovine albumin. Which sample(s) contain horse blood?
Correct Answer: B
Rationale: The correct answer is B (sample B) because the double-diffusion test in agar against antibody to bovine albumin is specific for detecting the presence of bovine albumin. Since horse blood does not contain bovine albumin, sample B must contain horse blood. Sample A does not contain horse blood as it would not react with the antibody to bovine albumin. Both samples (C) cannot contain horse blood because the test is specific for bovine albumin. Neither sample (D) is incorrect because sample B does contain horse blood.
Question 5 of 5
If you measure the ability of cytotoxic T cells from an HLA-B27 person to kill virus X-infected target cells, which one of the following statements is CORRECT?
Correct Answer: B
Rationale: The correct answer is B: Only virus X-infected cells of HLA-B27 type will be killed. This is because cytotoxic T cells recognize antigens presented by HLA molecules. In this case, the cytotoxic T cells from an HLA-B27 person will specifically target virus X-infected cells that display antigens on HLA-B27 molecules. Choice A is incorrect because not all virus X-infected cells will be killed, only the ones with specific HLA molecules. Choice C is incorrect as not all HLA-B27 cells will be killed, only the virus-infected ones. Choice D is incorrect as the question specifically mentions virus-infected cells, not all HLA-B27 cells.