Which condition is an example of Type IV hypersensitivity?

Correct Answer: A

Rationale: The correct answer is A: Multiple sclerosis. Type IV hypersensitivity involves T cell-mediated immune reactions, leading to tissue damage. In multiple sclerosis, myelin sheath destruction is caused by activated T cells attacking self-antigens. Incorrect choices: B: Grave's disease is an example of Type II hypersensitivity involving autoantibodies targeting specific cells. C: Anaphylaxis is a Type I hypersensitivity reaction mediated by IgE antibodies causing rapid and severe allergic reactions. D: Eczema is a chronic inflammatory skin condition involving complex immune mechanisms not specific to Type IV hypersensitivity.

Correct Answer: B

Rationale: Granuloma formation is characterized by the persistent recruitment of macrophages around undigested antigens. Initially, macrophages attempt to phagocytose the antigen but fail to digest it completely, leading to the formation of a granuloma. This process is a protective mechanism to isolate the antigen and prevent its spread. IgE-mediated mast cell activation (choice A) is associated with allergic reactions, not granuloma formation. Deposition of immune complexes in tissues (choice C) is linked to immune complex-mediated diseases, not granuloma formation. Complement-mediated cell lysis (choice D) involves the destruction of target cells by the complement system, which is not directly related to granuloma formation.

Correct Answer: A

Rationale: The correct answer is A. If the client states they don't need to go to the hospital after using the epinephrine autoinjector, additional instruction is needed. The rationale is that after using an epinephrine autoinjector, it is crucial to seek medical attention immediately due to the potential for severe allergic reactions. Choice B is incorrect because carrying two autoinjectors is recommended in case the first dose is not effective. Choice C is incorrect as it demonstrates good practice in tracking the expiration date. Choice D is incorrect as it is acceptable to inject through clothes in an emergency situation.

Correct Answer: C

Rationale: Rationale: VDJ gene rearrangement occurs during lymphocyte development to generate diverse antigen receptors. This process occurs in the bone marrow, specifically in the early stages of B cell development. In the bone marrow, B cell precursors undergo VDJ recombination to create unique antibody specificity. Germinal centers are sites for B cell activation and proliferation, not gene rearrangement. Lymph nodes and spleen are secondary lymphoid organs where mature lymphocytes are activated, not where VDJ recombination occurs.

Correct Answer: E

Rationale: The correct answer is E because a TH2 immune response is associated with isotype switching to IgE and secretion of IL-4, which are essential for allergic responses. Activation of macrophages is not associated with a TH2 response. Resistance to Leishmania infection is mediated by a TH1 response, not TH2.