What substance do mast cells release upon injury or irritation?

• A. Clotting factors and platelets
• B. Histamine and inflammatory mediators
• C. Antibodies against pathogens
• D. Cytokines to attract macrophages

Answer: (B)

Mast cells release histamine and inflammatory mediators in response to injury or irritation, making this the correct choice. Histamine plays a crucial role in the inflammatory response by causing vasodilation and increasing the permeability of blood vessels, which allows immune cells and substances to enter the affected tissue more easily. This release initiates the body's defense against potential pathogens and facilitates healing.

Additionally, mast cells contribute to the broader inflammatory response through the release of other mediators, such as cytokines and leukotrienes, which can recruit other immune cells to the site of injury. This process is vital for controlling infection and promoting tissue repair.