The lung as an immunologic organ.

Considerable information exists and is reviewed and summarized to support the suggestion that the lungs are a major contributor to immunity. The immune response differs in quantity and quality in different parts of the lung and this response depends in magnitude and type on a number of factors such as previous exposure, nature of the antigen, amount, etc. The ways in which these pulmonary immune responses are regulated and may be augmented and harnessed are discussed.