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

In a complete blood count (CBC), which component is primarily measured to assess the body's immune function?

1. Red blood cells

2. White blood cells

3. Platelets

4. Hemoglobin

The correct answer is: White blood cells

The component primarily measured to assess the body's immune function in a complete blood count (CBC) is white blood cells. White blood cells, or leukocytes, play a crucial role in the immune response, as they are involved in defending the body against infections, foreign substances, and diseases. Their count and differential can provide significant insights into a person's immune status, including the presence of infections, inflammatory conditions, and certain hematological disorders. While red blood cells, platelets, and hemoglobin are important components of the CBC, they do not primarily reflect the body's immune function. Red blood cells are mainly involved in transporting oxygen and carbon dioxide, hemoglobin is the protein within red blood cells that carries oxygen, and platelets are essential for blood clotting. Thus, white blood cells are the most directly connected to assessing the immune response within the body.