Amit started sneezing and wheezing after reaching Shimla

Amit started sneezing and wheezing after reaching Shimla, from Delhi. But on return, the symptoms disappeared. What is such a response called? How does the body produce it?

The response such as sneezing and wheezing for no explained reason is called allergy. The substances against which the body’s immune system shows such exaggerated response are called allergens. Body responds to allergens by producing a type of antibody. Most common allergens are pollen grains, dust, etc.