Characterization of scavenger receptor activity in resident human lung macrophages.
We characterized scavenger receptor pathways of human alveolar macrophages and cultured monocytes using radiolabeled maleylated bovine serum albumin (MAL-BSA) and acetylated low-density lipoprotein (Ac-LDL) as ligands. Human alveolar macrophages and cultured human monocytes degraded both MAL-BSA and Ac-LDL. Both ligands were bound and degraded in a specific and saturable fashion. Specificity of degradation was tested using excess MAL-BSA and Ac-LDL, polyanionic compounds, and alpha-casein as inhibitors. Alveolar macrophages utilized the classical scavenger receptor pathway to degrade MAL-BSA and Ac-LDL. In contrast, cultured monocytes utilized two receptor pathways to degrade MAL-BSA: the classical scavenger receptor pathway and a secondary alpha-casein-inhibitable pathway. These results demonstrate differences in the activities of receptor systems in cultured monocytes compared to alveolar macrophages.
McCusker
K
K
Pulmonary Division, University of Tennessee, Memphis.
Hoidal
J
J
D006801:Humans; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism; D009000:Monocytes / Q000378:metabolism*; D010587:Phagocytosis; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*
D011956:Receptors, Cell Surface