What substance is released in the body during any kind of immune response?

The correct substance that is released in the body during any immune response is histamine. Histamine plays a crucial role in the immune system as a mediator of allergic reactions and responses to injury or pathogens. When the immune system detects an invader, such as bacteria or allergens, mast cells and basophils release histamine. This release causes blood vessels to dilate and increases their permeability, allowing immune cells to reach the affected area more effectively.

Histamine is integral to the inflammatory response, leading to typical symptoms such as swelling, redness, and itching. While the other substances listed also participate in immune responses, histamine is notably involved during various immune reactions, particularly those linked to allergies and anaphylaxis. Cytokines are signaling proteins that facilitate communication within the immune system but are not specifically released during every immune response in the same immediate way as histamine. Leukotrienes and prostaglandins are also mediators associated with inflammation, but they have more specific roles and do not uniformly respond to all types of immune triggers as histamine does.