ASCP (American Society for Clinical Pathology) Phlebotomy Technician Certification Practice Exam

Eosinophils play a crucial role in the immune system, particularly in combating allergic reactions and parasitic infections. These white blood cells are primarily responsible for responding to allergens and helminths (parasitic worms). When the body encounters a parasite, eosinophils can release enzymes and toxic granules that target and help destroy these invaders. Additionally, they contribute to the regulation of inflammatory responses, especially in allergic manifestations, such as asthma and hay fever, by modulating the activity of other immune cells.

The other choices are associated with different aspects of the immune system or bodily functions. For instance, fighting viral infections is primarily the role of lymphocytes, while blood clotting is chiefly initiated by platelets. The transportation of nutrients is mainly a function of red blood cells and the plasma. Thus, the specificity of eosinophils in dealing with allergic reactions and parasites underlines their critical role in the immune response.