American Society for Clinical Pathology (ASCP) Histotechnician Certification Practice Exam

What is the primary function of leukocytes in the body?

1. Transporting oxygen to tissues

2. Defending the body against bacteria and viruses

3. Clotting blood to prevent hemorrhage

4. Producing antibodies for immunity

The correct answer is: Defending the body against bacteria and viruses

The primary function of leukocytes, or white blood cells, is to defend the body against bacterial and viral infections, which is reflected in the correct answer. These cells play a crucial role in the immune system. They identify and neutralize pathogens, such as bacteria and viruses, that can cause disease. There are different types of leukocytes, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils, each with specialized functions in the immune response. In contrast, while other options mention important bodily functions—transporting oxygen is the role of erythrocytes (red blood cells), clotting is primarily managed by platelets, and antibody production is performed by specific types of lymphocytes—they do not encompass the central role that leukocytes have in immune defense. Thus, option B accurately highlights the essential and primary function of leukocytes in the body.