Question

Mast cells secrete a protein that causes the dilation of blood vessels. The protein is?
A) Pyrogens
B) Histamine
C) Interferon
D) None of the above

Answer 1

Hint: Mast cells arise from pluripotent progenitor cells of the bone marrow, and grow fully under the impact of the c-kit ligand and stem cell factor in the presence of other different growth factors. Mast cells also play a crucial role in the evolution of allergies.

Complete step-by-step answer:
Like circulating basophils, mast cells have large cytoplasmic granules that contain histamines and other pharmacologically active substances. So mast cells secrete histamine that dilates blood vessels.
Pyrogens are the substances released by bacteria during fever. Antibodies are released when a foreign particle invades our immune system an antigen-antibody complex is formed and the invading antigen killing takes place.
Interferons are a large family of cytokines involved in antiviral defence, cell growth regulation, and immune activation. In 1957 the first cytokine to be described as interferon. Human interferons have been classified into three major types- type I IFN, type II IFN and TYPE III IFN based on the type of receptor through which they signal.

Additional information Basophils and mast cells possess high-affinity receptors for one type of antibody, known as IgE. Basophils have lobed nuclei and stain with the basic dye methylene blue. It comprises less than 1% of total WBCs.
Hence the correct answer is option (B)histamine.

Note: The common myeloid progenitor cells give rise to granulocytes (neutrophils, eosinophils, basophils, mast cells), monocytes, macrophages, erythrocytes, and megakaryocytes. Basophils are non-phagocytic and release substances that cause an allergic response. These substances causing allergic responses are histamine, prostaglandins, serotonin, and leukotrienes.