Allergens like pollen are nothing more than foreign plant antigens. The stimulus for sneezing gets triggered when allergens first enter the nasal tissue. Pollen allergens encounter the plasma cells in the nose, which respond by producing antibodies. These antibodies attach to mast cells, which are white blood cells containing the chemical histamine. As more antibodies are produced, they cause the mast cells to release histamine. Histamine then produces allergy symptoms. A stuffy and runny nose, sneezing and watery eyes help to remove the invading pollen. Medications called antihistamines may be used to help alleviate severe allergy symptoms.
Update Date 12/3/2012
Updated by: Paula J. Busse, MD, Assistant Professor of Medicine, Division of Clinical Immunology, Mount Sinai School of Medicine, New York, NY, Review provided by VeriMed Healthcare Network.