Immunochemical studies of the protein fraction of pulmonary surface active material.

SUMMARy _ Rabbits were immunized to pulmonary surface active material that was isolated from lungs of dogs. The resulting antiserum was directed against 3 antigenic components, 2 of which were im­ munologically identical to dog serum proteins. The third antigen was not contained in dog serum or plasma. Immunofluorescent labeling indicated that this antigen originated in the alveoli of dog lungs.