[Mechanisms of clearance of foreign bodies by macrophages].
Macrophages have specific functions related to the sites where they are found. Pulmonary alveolar macrophages (PAM) may play an important role the clearance of invading and degenerative substances from the alveolar spaces. To clarify the mechanisms of the clearance by macrophages, we studied the role of scavenger receptors (SR) and Fc receptors (FcR) of PAM. 1) SR: Expression and localization of SR in human PAM. Type I and II SRs were expressed in human PAM, and the two SRs were confirmed in the same cells by double staining method using polyclonal antibodies to the SRs. These SRs were localized on the cell membrane and the endosome in part. The expression of SR in PAM from normal nonsmokers, smokers and patients with pneumoconiosis was studied, but there were no differences among these groups. Kinetics of SR and acetylated low density lipoprotein (acLDL) in PAM. SR recognized acLDL, and SR and acLDL-Au conjugates were concentrated in a coated pit 2 min after incubation. The conjugates were then internalized in the endosome 5 min after incubation. A few acLDL-Au conjugates were present in the endosome near the nucleus, but most of them were found in the lysosome 10 min after incubation. SR was found in the Golgi apparatus 15 min after incubation. These results suggest that SR in PAM may play an important role in the removal of alveolar surfactant. 2) FcR: Effects of FcR mediated phagocytosis on O2-release and phagosome-lysosome fusion in the phagosome of PAM.(ABSTRACT TRUNCATED AT 250 WORDS)
Suga
M
M
First Department of Internal Medicine, Kumamoto University School of Medicine.
Mori
T
T
Ando
M
M
Naito
M
M
Takahashi
K
K
D000818:Animals; D002478:Cells, Cultured; D006801:Humans; D008087:Listeria / Q000276:immunology*; D016676:Macrophages, Alveolar / Q000276:immunology*; D009163:Mycobacterium bovis / Q000276:immunology*; D010587:Phagocytosis; D011817:Rabbits; D011961:Receptors, Fc / Q000502:physiology; D015003:Yeasts / Q000276:immunology
D011961:Receptors, Fc