Emergency Medical Technician (EMT) Intermediate Practice Exam

Which chemicals released by the immune system are responsible for allergic reactions?

1. Cytokines and interleukins

2. Histamines and leukotrienes

3. Prostaglandins and thromboxanes

4. Antibodies and antigens

The correct answer is: Histamines and leukotrienes

The chemicals primarily responsible for allergic reactions are histamines and leukotrienes. Histamines are produced by mast cells and basophils in response to allergens. They play a key role in the inflammatory response, causing symptoms such as itching, swelling, and increased mucus production. When histamines bind to their receptors in various tissues, they lead to the classic signs of an allergic reaction, such as redness and swelling. Leukotrienes, on the other hand, are inflammatory mediators that contribute to the bronchoconstriction and increased vascular permeability associated with allergic responses, particularly in conditions like asthma. They are involved in regulating the inflammatory response and can lead to symptoms such as wheezing and difficulty breathing. In contrast, while cytokines and interleukins are important in the immune response and can modulate inflammation, they are not the primary drivers of the symptoms seen in allergic reactions. Prostaglandins and thromboxanes are also involved in various inflammatory processes but have a different role compared to histamines and leukotrienes. Lastly, antibodies and antigens are critical to the immune system but do not directly cause the manifestations of allergic reactions; rather, antibodies can mediate the response to allergens.