Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

Which blood component is primarily involved in the immune response?

1. Plasma

2. Erythrocyte

3. Leukocyte

4. Thrombocyte

The correct answer is: Leukocyte

The primary blood component involved in the immune response is leukocytes, also known as white blood cells. These cells are crucial for defending the body against infections, foreign substances, and disease. They play a vital role in identifying pathogens, such as bacteria and viruses, and responding to them by attacking and eliminating these threats. Leukocytes are diverse and include various types, such as lymphocytes, which are central to adaptive immunity, and neutrophils, which are key players in the innate immune response. Collectively, they work together to produce antibodies, engulf and destroy harmful agents, and orchestrate the overall immune response. Other blood components, such as plasma, which is the liquid portion of blood containing nutrients, hormones, and waste products, do play supportive roles but are not directly responsible for immune responses. Erythrocytes, or red blood cells, are primarily involved in oxygen transport and do not have a role in immunity. Thrombocytes, or platelets, are mainly involved in blood clotting and do not participate in the immune process. Thus, leukocytes stand out as the primary contributors to the immune defense in the bloodstream.