Question

Which of the following cells is not a phagocytic cell?
A) Macrophage
B) Monocyte
C) Neutrophil
D) Basophil

Answer 1

Hint: Phagocytosis is the process of engulfing foreign particles by forming an internal compartment called phagosome inside which cellular enzymes degrade the foreign particle. Phagocytic cells are white blood cells that engulf and degrade foreign particles and microorganisms by the process of phagocytosis.

Complete step by step answer: Basophils are not phagocytic cells. They are granular leukocytes that accumulate at sites of allergy. They fight against parasitic infections and contain heparin which helps in thinning of the blood. At times of encounter with allergens, they release histamine which leads to inflammation. Low levels of basophils in the blood are observed in case of infections or allergies. Phagocytosis is a process in which certain immune cells engulf pathogens that make an entry into the body, break down the pathogen and present it to the B-cells via MHC-II proteins.
i. Macrophage: These are phagocytic leucocytes. At times of inflammation, monocytes develop into macrophages. They engulf and destroy ingested particles with the help of digestive enzymes. They also act as scavengers which help in the removal of dead cells from the body.
ii. Monocyte: These are the largest leukocytes that differentiate into macrophages. They perform three main functions in the body; phagocytosis and removal of foreign substances, secrete chemokines and present antigens. They are capable of recognizing danger signals and are mostly present in blood and spleen. High levels of monocytes indicate chronic infection.
C. Neutrophils increase at times of inflammation from bone marrow to the site of infection. Phagocytosis by neutrophils occurs in about 9 minutes. Secretions of neutrophils stimulate macrophages and monocytes for phagocytosis. Neutrophils are high motile phagocytes which show the first line of defence of innate immunity.
Hence, the correct answer is option D.

Note: White blood cells or leukocytes the cells that protect the body against disease-causing microorganisms. All white blood cells are produced from bone marrow. There are two types of WBCs namely; granulocytes and agranulocytes. Agranulocytes are monocytes and lymphocytes, and granulocytes are eosinophils, basophils and neutrophils.