Immunology of the lung

Recent conceptual advances in immunology are reviewed. Although immune reactions take place in all organs, those occurring in the lung were chosen for illustrative purposes. The lung's enormous surface area has direct contact with the external environment through the airways and receives all of the cardiac output, a situation which exposes it to numerous, potentially harmful agents. The four basic types of immune responses are depicted as ending with tissue injury, but in most instances these reactions protect the host from disease. Manipulation of the immune system with transfer factor, new routes of immunization with existing vaccines, and other forms of immunotherapy are potential avenues for future management of disease.