The correct option is Neutrophils.
Explanation
White Blood Cells (Leucocytes) are the key components of the immune system, classified into granulocytes and agranulocytes. Phagocytosis is the specific cellular process of engulfing and digesting solid substances, such as bacteria, foreign particles, and dead cells. The primary function of specific leukocytes is to act as phagocytes to neutralize pathogens.
Option Analysis
- Neutrophils is Correct: Neutrophils are the most abundant leukocytes, constituting approximately 60-65% of the total WBC count. They are highly active phagocytic cells that rapidly migrate to sites of infection to engulf and destroy bacteria and other pathogens. Along with monocytes, they are the body's main phagocytes.
- Basophils is Incorrect: Basophils are the least abundant WBCs (0.5-1%). Their primary role is to secrete inflammatory mediators such as histamine, serotonin, and heparin. They are involved in inflammatory reactions rather than direct phagocytosis.
- Eosinophils is Incorrect: Eosinophils (2-3%) are primarily involved in resisting parasitic infections and modulating allergic reactions. While they have limited phagocytic ability, it is not their primary function compared to neutrophils.
- Lymphocytes is Incorrect: Lymphocytes (20-25%) are central to the adaptive immune system. They differentiate into B-cells (which produce antibodies) and T-cells (which destroy infected host cells). They do not function primarily by engulfing pathogens.
Key Takeaway
Neutrophils and Monocytes are the primary phagocytic cells in the human body responsible for the non-specific defense mechanism of engulfing and destroying foreign microbes.