Pulmonary lavage is easily obtainable and can be taken at various time intervals from the same animal (large) without killing the animal. Pulmonary lavage contains lipoprotein surfactant, lung cells, macrophages, enzymes released from macrophages, and enzymes associated either with the protein part or the lipid part of the lung surfactant. Lung surfactants are important for the stability of alveoli; lipids not associated with lung surfactant may be related to lung cell membranes. Lung tissue is capable of synthesizing lung surfactant and lipids. The alveolar macrophages are vital entities of the mammalian immune system. In the latter capacity, the macrophage depends upon plasma membrane activity for migration recognition, activation, phagocytosis and attachment to substrate tissue. Thus, lavage can be used as a probe for early detection of lung cell damage, and of the lung immune and biosynthetic function