some allergens causes sneezing $ wheezing in human beings .what causes this type of response by the body.

Actually it is our immune system that cause such type of response in our body. Immune system enables our body to react against allergens. Our immune system generally identify allergen and then it react to that particular allergen by producing IgE type of antibodies. The main function of these antibodies is to release such chemicals that cause allergic reactions like sneezing and wheezing.