During an allergy workup, which laboratory finding indicates an allergic response is in progress?

During an allergy workup, which laboratory finding indicates an allergic response is in progress?

• A. Increased eosinophil level
• B. Decreased platelets
• C. Increased lymphocyte count
• D. Decreased immunoglobulin level

Answer: (A)

During allergic inflammation, eosinophils are drawn to the site of allergen exposure and their numbers rise in the blood when the reaction is active. Eosinophils respond to IL-5 from Th2 cells and to chemotactic signals from activated mast cells; once activated, they release granule proteins that amplify inflammation and tissue damage, a hallmark of ongoing allergic processes such as rhinitis, asthma, or dermatitis. This elevation indicates an active allergic response. In contrast, decreased platelets aren’t related to allergy, increased lymphocytes often point to viral or other non-allergic immune processes, and decreased immunoglobulins suggest a humoral deficiency rather than active allergy. So the increased eosinophil level best indicates an ongoing allergic response.

During allergic inflammation, eosinophils are drawn to the site of allergen exposure and their numbers rise in the blood when the reaction is active. Eosinophils respond to IL-5 from Th2 cells and to chemotactic signals from activated mast cells; once activated, they release granule proteins that amplify inflammation and tissue damage, a hallmark of ongoing allergic processes such as rhinitis, asthma, or dermatitis. This elevation indicates an active allergic response. In contrast, decreased platelets aren’t related to allergy, increased lymphocytes often point to viral or other non-allergic immune processes, and decreased immunoglobulins suggest a humoral deficiency rather than active allergy. So the increased eosinophil level best indicates an ongoing allergic response.