Question

Which WBC plays a significant role in allergic reactions?
(a) Monocytes
(b) Basophils
(c) Lymphocytes
(d) Erythrocytes

Answer 1

An allergy is a set of conditions in the body caused due to hypersensitivity of the immune system to generally harmless substances found in the environment. Various WBCs are involved in controlling the immune response.

Complete step-by-step answer:
- WBCs, also known as leukocytes are distinguished as granulocytes or agranulocytes, and further divided as basophils, eosinophils, neutrophils, monocytes, and lymphocytes.
- Basophils are the least common type of granulocyte, forming 0.5-1.0 % of the total circulating WBCs. They are however the largest granulocyte.

- The main function of the basophil is to release histamine during an allergic reaction. Histamine is a molecule that regulates inflammation and causes vasodilation. It is also a neurotransmitter in the body. Additionally, basophils also release serotonin and heparin.
- They play a role in parasitic infections and allergies.
So, the correct answer is ‘Basophils’.

Additional information:
- Basophils’ name is derived from the fact that they are susceptible to staining from basic dyes. Their granules are stained dark blue.
- Erythrocytes are red blood cells or RBCs. These cells are present in blood and are different from WBCs as they are anucleated. RBCs are essential for the transport of oxygen throughout the body.
- Monocytes and neutrophils are phagocytic in nature. They engulf foreign bodies and eliminate them by phagocytosis.
- Lymphocytes are the main cells found in the lymph. They consist of T-cells, B-cells, and natural killer cells.

Note:
- A reduction in basophils is indicative of stress reactions, hyperthyroidism, prolonged exposure to steroids, and autoimmune urticaria in some cases.
- Eosinophils have a larger role in modulating allergic reactions than basophils, hence, in a mention of both of these options, opt for eosinophils.