[Pulmonary surfactant and the immune system]

Natural surfactant, a mixture of lipids and proteins is potentially immunogenic. Frequent therapeutic and prophylactic use of exogenous lung surfactants necessitates a review of the data on its influence and relation to the immune system. Detection of circulating surfactant-antisurfactant immune complexes in the serum of newborn with respiratory distress syndrome and sporadically of free antisurfactant antibodies was not associated with any other specific symptoms during short term survey. Several studies were unable to detect formation of specific surfactant protein B or C antibodies in response to treatment with bovine surfactants. However further and long term follow up of these neonates especially during newly acquired lung diseases is desirable. In addition to its antigenicity, surfactant participates in a complex manner in the local immune response of the lung. Due to its direct bactericidal effects for some bacteria and various interactions with alveolar macrophages, lymphocytes and monocytes, surfactant is specifically involved in the defense of pulmonary pathogens. Furthermore there is evidence for a modulation and suppression of immune responses in the terminal alveoli by surfactant. These immunological aspects of lung surfactant need further study.