What antibody mediates Type I hypersensitivity?

Correct Answer: B

Rationale: The correct answer is B: IgE. In Type I hypersensitivity reactions, IgE antibodies are involved. Firstly, upon initial exposure to an allergen, B cells produce IgE antibodies specific to that allergen. IgE antibodies then bind to mast cells and basophils. Upon subsequent exposure to the same allergen, it cross-links the IgE antibodies on mast cells and basophils, leading to degranulation and release of inflammatory mediators like histamine. This results in the symptoms of Type I hypersensitivity reactions. Choice A (IgA) is incorrect because IgA is mainly involved in mucosal immunity. Choice C (IgG) is incorrect because while IgG can be involved in Type II and Type III hypersensitivity reactions, it is not the primary antibody in Type I hypersensitivity. Choice D (IgM) is incorrect because IgM is typically involved in the primary immune response, not in Type I hypersensitivity reactions.

Correct Answer: D

Rationale: The correct answer is D: Systemic lupus erythematosus (SLE). Type I hypersensitivity involves IgE-mediated reactions to allergens, leading to immediate responses like asthma, food allergies, and anaphylaxis. SLE is an autoimmune disease involving immune complexes and not IgE antibodies. Therefore, SLE is not directly associated with Type I hypersensitivity. Asthma, food allergies, and anaphylaxis are all examples of Type I hypersensitivity reactions due to IgE-mediated mechanisms.

Correct Answer: B

Rationale: The correct answer is B: Urushiol oil. Urushiol oil is the allergen in poison ivy that triggers contact dermatitis. When urushiol oil comes into contact with the skin, it can cause an allergic reaction leading to redness, itching, and inflammation. Histamine (choice A) is a compound released by the body in response to allergens but is not the specific chemical in poison ivy. Lipopolysaccharide (LPS) (choice C) is a component of the outer membrane of certain bacteria and not present in poison ivy. C3a (choice D) is a complement protein involved in the immune response but not related to poison ivy dermatitis.

Correct Answer: C

Rationale: The correct answer is C: "You should be seen in the clinic right away." This response is appropriate because poison ivy rashes can worsen and may require prescription medications like corticosteroids. Seeing a healthcare provider ensures proper diagnosis and treatment. A: "Antihistamines do not help poison ivy." - Incorrect, as antihistamines may provide some relief for itching but are not the primary treatment for poison ivy rashes. B: "There are different antihistamines to try." - Incorrect, as trying different antihistamines may not address the underlying issue of poison ivy exposure. D: "You will need to take some IV steroids." - Incorrect, as IV steroids are typically reserved for severe cases and should be prescribed by a healthcare provider after evaluation.

Correct Answer: E

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.