An important function of the immune system is fighting off infections. To do this, the immune system recognizes microorganisms as foreign to the person and produces proteins (antibodies) that join with the microorganisms so they can be removed from the body. In autoimmune disorders, the body mistakenly reacts against a person's own tissues as if they were foreign and were causing an infection. In autoimmune disorders that involve the lungs, the immune system attacks and damages lung tissue. Commonly, people cough up blood (hemoptysis) and have trouble breathing. Often, the kidneys are affected too.
Some disorders of the lungs are specific diseases (for example, asthma or chronic obstructive pulmonary disease), but many autoimmune disorders are syndromes.
Syndromes of lung autoimmune disorders can overlap. Diffuse alveolar hemorrhage involves bleeding into the lungs. Pulmonary-renal syndrome involves bleeding into the lungs (which occurs in diffuse alveolar hemorrhage) plus kidney dysfunction. Goodpasture syndrome results when a particular autoimmune disorder causes pulmonary-renal syndrome.
Last full review/revision May 2013 by Marvin I. Schwarz, MD