What is the role of eosinophils in allergic reactions?

What is the role of eosinophils in allergic reactions?

• A. Inhibit inflammatory response to histamine
• B. Increase histamine release
• C. Stimulate platelet aggregation
• D. Decrease immunoglobulin production

Answer: (A)

Eosinophils in allergic reactions help regulate the inflammation set off by the allergic cascade, acting to dampen the effects of histamine. After mast cells release histamine during the immediate allergic response, eosinophils arrive at the site and can counteract that histamine-driven inflammation. They do this in part by releasing enzymes such as histaminase that degrade histamine, thereby reducing vascular leakage, edema, and bronchoconstriction that histamine promotes. This modulatory role helps explain why the best answer describes eosinophils as inhibiting the inflammatory response to histamine. Eosinophils are also involved in the later stages of allergic inflammation, releasing cytotoxic proteins and other mediators that can contribute to tissue injury and remodeling, which is distinct from the initial histamine surge. This broader activity is why they’re associated with sustained inflammation in conditions like asthma and allergic rhinitis, but the key point here is their capacity to temper the immediate histamine effect. The other options don’t fit the typical role of eosinophils: they do not primarily increase histamine release, they do not promote platelet aggregation, and they do not suppress immunoglobulin production.

Eosinophils in allergic reactions help regulate the inflammation set off by the allergic cascade, acting to dampen the effects of histamine. After mast cells release histamine during the immediate allergic response, eosinophils arrive at the site and can counteract that histamine-driven inflammation. They do this in part by releasing enzymes such as histaminase that degrade histamine, thereby reducing vascular leakage, edema, and bronchoconstriction that histamine promotes. This modulatory role helps explain why the best answer describes eosinophils as inhibiting the inflammatory response to histamine.

Eosinophils are also involved in the later stages of allergic inflammation, releasing cytotoxic proteins and other mediators that can contribute to tissue injury and remodeling, which is distinct from the initial histamine surge. This broader activity is why they’re associated with sustained inflammation in conditions like asthma and allergic rhinitis, but the key point here is their capacity to temper the immediate histamine effect.

The other options don’t fit the typical role of eosinophils: they do not primarily increase histamine release, they do not promote platelet aggregation, and they do not suppress immunoglobulin production.