WBR0491

Author	[[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Alison Leibowitz)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Immunology
Sub Category	SubCategory::Pulmonology
Prompt	[[Prompt::A 7-year-old boy is brought to the emergency room for a severe cough. The mother reports that when her son woke up he started coughing non-stop and subsequently turned a shade of blue. The mother mentions that this is not the first occurance, as he has been having severe coughing fits at night and following gym class. He is diagnosed with asthma. Which of the following mediators is involved in the class switching of immunoglobulin to IgE which is involved in the pathophysiology of the patient's condition?]]
Answer A	AnswerA::Interleukin 1
Answer A Explanation	[[AnswerAExp::Interleukin 1 impacts the activity of hypothalamus, the thermoregulatory center, which leads to a raise of a body temperature. Interleukin 1 is not involved in asthma.]]
Answer B	AnswerB::Interleukin 2
Answer B Explanation	[[AnswerBExp::Interleukin 2, secreted by helper T-cells, is necessary for the growth, proliferation, and differentiation of T cells to become 'effector' T cells. Interleukin 2 is not involved in asthma.]]
Answer C	AnswerC::Interleukin 3
Answer C Explanation	[[AnswerCExp::Interleukin 3, secreted by basophils and activated T cells, supports growth and differentiation of T cells from bone marrow in an immune response. Interleukin 3 is not involved in asthma.]]
Answer D	AnswerD::Interleukin 4
Answer D Explanation	[[AnswerDExp::Interleukin 4 induces B-cell class switching to IgE, and up-regulates MHC class II production. IL-4 decreases the production of Th1 cells, macrophages, IFN-gamma, and dendritic cell IL-12.]]
Answer E	AnswerE::Interleukin 5
Answer E Explanation	[[AnswerEExp::Interleukin 5 is a major regulator of eosinophil accumulation in tissues, and can modulate eosinophil behavior at every stage from maturation to survival.]]
Right Answer	RightAnswer::D
Explanation	[[Explanation::The patient is suffering from coughing fits at night and following exercise, which are consistent with a diagnosis of asthma. Both interleukin 4 and 5 are involved in asthma. Interleukin 4 promotes class switching of immunoglobulin into IgE and Interleukin 5 plays a role in the activation and proliferation of eosinophils. The image displayed below summarizes the roles of interleukins and the cells that secrete them. Educational Objective: Interleukin 4 induces B-cell class switching to IgE and is critical in the pathophysiology of asthma. References: First Aid 2014 page 205]]
Approved	Approved::Yes
Keyword	WBRKeyword::Interleukin, WBRKeyword::asthma, WBRKeyword::immunoglobulin, WBRKeyword::respiratory system, WBRKeyword::eosinophil, WBRKeyword::coughing
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::