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Intracellular surfactant removal from phagocytized minerals: development of a fluorescent method using a BODIPy-labeled phospholipid.

Authors
Das-AR; Cilento-EV; Keane-MJ; Wallace-WE
Source
Inhal Toxicol 2000 Aug; 12(8):765-781
NIOSHTIC No.
20020650
Abstract
Lung surfactant serves as a protective coating when adsorbed on particle surfaces, so its removal or rate of removal in vivo may affect expression of mineral cytotoxicity. Removal of phospholipid surfactant components from the surface of mineral particles ingested by alveolar macrophages (AM) was measured using fluorescence microscopy. Dipalmitoylphosphatidylcholine with a fluorescent label (BODIPY(trade mark)) substituted for C1-C4 on the second acyl chain (DPPC*), was mixed with dioleoylphosphatidylcholine (DOPC) to coat respirable quartz and kaolin particles. Fluorescence from quartz or kaolin particles of 3-4, 5-6 and 8-9 microm size decreased in intensity with increasing ratios of DOPC/DPPC* for the same DOPC concentration of 0.4 mg/ml. There was a direct correlation between fluorescence and residual phospholipid surfactant remaining on particles using phospholipase A2 (PLA(2)) digestion in a cell-free system, indicating that the presence of the fluorophore on DPPC did not hinder enzymatic recognition. Lavaged primary AM obtained from male Fischer rats were challenged in vitro with DOPC/DPPC* (10:1 mol:mol) coated particles at 50 microg particles/10(6) cells. In contrast to the biexponential response seen in cell-free experiments, the rate of fluorescence decay from ingested coated quartz or kaolin particles over 7 days was monoexponential, with the same t(1/2) (41 h) for each dust. This study suggests that the rate of phagolysosomal digestion and removal of the adsorbed surfactant is not a determinant of the different mineral-specific pathogenicities or toxicities of quartz and kaolin, although residual fluorescence remained on particles even after 7-8 days.
Keywords
Phagocytes; Phagocytic-activity; Minerals; Phospholipids; In-vivo-studies; Cytotoxicity; Microscopy; Respirable-dust; Quartz-dust; Lung-disorders
CODEN
INHTE5
CAS No.
14808-60-7
Publication Date
20000801
Document Type
Journal Article
Email Address
ecilento@wvu.edu
Fiscal Year
2000
NTIS Accession No.
NTIS Price
Issue of Publication
8
ISSN
0895-8378
NIOSH Division
HELD
Source Name
Inhalation Toxicology
State
WV
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