A student on a school trip started sneezing and wheezing soon after reaching the hill station for no explained reasons. But, on return to the plains, the symptoms disappeared. What is such a response called? How does the body produce it?

• Many of us are sensitive to some particular particles in the environment.

• Responses such as sneezing and wheezing for no explained reasons are called Allergy.

• Allergens are the substances that produced such immune responses.

• Allergy is produced in a body due to the release of chemicals like histamine and serotonin from mast cells.

• The body produces IgE type of antibody against allergens as a response.

• The most common example of allergens is pollen grains, dust, etc.

• Symptoms of allergic reactions include sneezing, watery eyes, running nose and difficulty in breathing.