What is the primary function of mast cells in allergic reactions?

• A. They produce antibodies
• B. They release histamines and other mediators
• C. They neutralize toxins
• D. They inhibit virus replication

Answer: (B)

Mast cells play a crucial role in allergic reactions primarily through their ability to release histamines and other mediators. When an allergen is encountered, mast cells, which are strategically located in tissues such as the skin, lungs, and lining of the gastrointestinal tract, become activated. Upon activation, they degranulate, releasing histamine and other inflammatory mediators like leukotrienes and prostaglandins.

Histamine specifically is responsible for many of the typical symptoms of an allergic reaction, including vasodilation, increased vascular permeability, and stimulation of nerve endings, which leads to itching or pain. This response is part of the body's defense mechanism against perceived threats, although in allergic individuals, it results in exaggerated responses to harmless substances.

The other options mention functions that are not associated with mast cells; they either relate to different immune system components (such as antibodies produced by B cells), focus on processes like toxin neutralization or viral inhibition which are managed by other aspects of the immune response. Thus, the primary and distinctive role of mast cells in allergic reactions is indeed centered around their release of histamines and other mediators.