What is sensitization?

• A. Allergic reaction development
• B. Acute poisoning symptoms
• C. Immune suppression
• D. Pesticide breakdown in the environment

Answer: (A)

Sensitivity occurs when the immune system becomes primed to a substance after initial exposure, so that subsequent encounters trigger an allergic response. The first contact may cause little or no reaction, but the body learns to recognize the substance and produces specific antibodies and memory cells. On later exposures, those antibodies can cross‑link on immune cells like mast cells, releasing chemicals that cause allergy symptoms. This is different from acute poisoning, which is about immediate toxic effects from a high dose; immune suppression, which reduces immune function; or environmental breakdown, which describes how a substance degrades in the environment. Understanding sensitization helps explain why repeated exposure to certain pesticides or allergens can lead to stronger reactions over time, highlighting the importance of protective measures and exposure control.