BINDING AND INGESTION OF HUMAN LACTOFERRIN BY MOUSE ALVEOLAR MACROPHAGES

59Fe-labelled human lactoferrin was found to be preferentially ingested by mouse alveolar macrophages (MAM) when compared to 59Fe-labelled human transferrin. The cells bound and ingested 125I-labelled iron-saturated and iron-free lactoferrin. The latter was digested faster (t 1/2 =5.8 hours), however, than the iron-saturated compound (t 1/2 =10.5 hours). The constant elimination of the Fe-lactoferrin complex by alveolar macrophages could enhance the bacteriostatic effect of lactoferrin in the pulmonary secretions.