What is the lag phase of the primary antibody response?

Correct Answer: B

Rationale: The lag phase of the primary antibody response refers to the time it takes for the immune system to generate specific antibodies after initial exposure to an antigen. The correct answer is B (5-10 days) because during this period, B cells are activated, undergo proliferation, differentiate into plasma cells, and start producing antibodies. This process takes time as the immune system needs to recognize the antigen, mount a response, and produce sufficient antibodies. Option A (1-3 days) is too short for the full activation and differentiation of B cells. Option C (10-15 days) is too long for the typical lag phase duration. Option D (No lag phase) is incorrect because there is always a lag phase before the peak antibody production in the primary immune response.

Correct Answer: B

Rationale: The correct answer is B because Type IV hypersensitivity reactions are delayed and T cell-mediated. Upon exposure to an antigen, sensitized T cells, specifically CD4+ T cells, release cytokines that recruit and activate macrophages and other effector cells, leading to tissue damage. Choice A is incorrect because Type I hypersensitivity reactions are immediate and IgE-mediated. Choice C is incorrect because immune complex-mediated hypersensitivity reactions are typically associated with Type III hypersensitivity. Choice D is incorrect because histamine release by mast cells is characteristic of Type I hypersensitivity reactions, not Type IV.

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.