What is required for sensitization in contact hypersensitivity?

Correct Answer: B

Rationale: The correct answer is B because sensitization in contact hypersensitivity requires T cell presentation of a hapten-modified antigen. This process activates T cells, leading to immune response. Antigen-antibody complex formation (A) is more related to immune responses in humoral immunity. Mast cell degranulation (C) is associated with allergic reactions, not contact hypersensitivity. Cytokine suppression (D) would hinder, not promote, the immune response needed for sensitization in contact hypersensitivity.

Correct Answer: C

Rationale: Granulomatous hypersensitivity is characterized by the formation of granulomas in response to persistent antigen exposure. Systemic lupus erythematosus (SLE) is an autoimmune disease involving immune complex deposition and inflammation, not granuloma formation. Crohn's disease, sarcoidosis, and tuberculosis are commonly associated with granulomatous hypersensitivity due to their chronic inflammatory nature and granuloma formation in affected tissues. SLE does not typically present with granulomas, making it the correct answer.

Correct Answer: C

Rationale: Step 1: Lyme disease is rarely fatal if treated promptly. Step 2: Choice C states that Lyme disease is usually fatal if not treated successfully, which is incorrect. Step 3: Therefore, this statement indicates a need for review as it spreads misinformation. Step 4: Choices A, B, and D are accurate and align with the information provided in the educational program. Step 5: In summary, the need to review the material is highlighted by the inaccurate statement in choice C, as the other choices provide correct information on Lyme disease.

Correct Answer: C

Rationale: The correct answer is C: Expressed on naïve T cells. L-Selectin is a cell adhesion molecule expressed on the surface of naïve T cells. It plays a crucial role in the initial attachment of T cells to high endothelial venules (HEV) in lymphoid tissues, facilitating T cell entry into lymph nodes. It specifically binds to ligands on HEV, allowing T cells to extravasate into lymphoid tissues. Choice A is incorrect because L-Selectin is primarily expressed on naïve T cells rather than effector T cells. Choice B is incorrect as L-Selectin is expressed on HEV, not by them. Choice D is incorrect because L-Selectin is involved in the initial attachment of T cells to endothelial cells, rather than being required for extravasation into tissues.

Correct Answer: D

Rationale: The correct answer is D because protection against Leishmania is mainly mediated by cell-mediated immune responses, not IgE antibodies. IgE is not typically involved in protection against intracellular parasites like Leishmania. A: Leishmania is indeed a unicellular parasite. B: Leishmania proliferates inside phagocytic cells, particularly macrophages. C: Leishmania is transmitted by sand flies during blood meals.