The walls of the alveoli are thin and fragile, and are easily damaged. As alveoli are destroyed, the lungs are able to transfer less and less oxygen to the bloodstream,causing shortness of breath during exercise and eventually even at rest. The lungs also lose their elasticity, so the patient experiences great difficulty exhaling. The bronchial tubes leading to the air sacs may collapse, which traps air in the lungs. This is the condition known as emphysema.
Neutrophil elastase is released by the white blood cells during times of inflammation.
In some people, who do not have enough protective AAT because their liver does not produce adequate amounts or cannot release it into the bloodstream, the neutrophil elastase attacks the walls of the alveoli causing irreversible damage. Most people with A1AD related emphysema do not lack the protein completely, rather they do not have enough of the protein to neutralize the action of neutrophil elastase. The first signs of A1AD related emphysema often appear between ages 20 and 40. The earliest symptom is usually shortness of breath following activity, as well as decreased exercise capacity and wheezing. Both the early age at which the disease is present and the fact that the disease most frequently appears in the lower rather than the upper lung regions helps distinguish A1AD related emphysema from other types of emphysema.