Microbiology Practice Exam

Among the following, which white blood cell is least abundant?

1. Basophil

2. Monocyte

3. Lymphocyte

4. Eosinophil

The correct answer is: Basophil

Basophils are indeed the least abundant type of white blood cell in the human body. They typically make up about 0.5% to 1% of the total white blood cell population. Their primary role is to participate in inflammatory responses and help fight off parasites. Basophils contain granules that store important chemicals such as histamine and heparin, which are released during allergic reactions and contribute to the body's inflammatory response. In contrast, lymphocytes, monocytes, and eosinophils have higher abundances in the blood. Lymphocytes are crucial for the adaptive immune response and account for approximately 20% to 40% of white blood cells. Monocytes, which eventually differentiate into macrophages and dendritic cells, comprise around 2% to 8% of the white blood cell count. Eosinophils play a role in combating parasitic infections and are involved in allergic responses, making up about 1% to 4% of the white blood cell population. Therefore, the information regarding the prevalence of these cell types in the bloodstream supports why basophils are considered the least abundant among them.