Experimental and calculated parameters on particle phagocytosis by alveolar macrophages.
Phagocytosis of three types of fluorescein-labeled test particles by rat alveolar macrophages (AM) were studied: spherical silica (3.2 microm), heat-killed Candida albicans (3.8 microm), and heat-killed Cryptococcus neoformans (6.1 microm) opsonized with specific IgG. These particles should attach to scavenger, mannose, and Fc receptors, respectively. Both control AM and AM pretreated for 20 h with interferon-gamma (12.5 or 50 U/ml) were studied. The sum of the number of attached and ingested particles per AM (accumulated attachment) was used as a measure of the attachment process, and the number of ingested particles per AM divided by the accumulated attachment (ingested fraction) was used as a measure of the ingestion process. The average ingestion time (IT), which is also a measure of the ingestion process, was calculated from the experimental data. The ingestion process was independent of the attachment process. IT increased with the time of observation. This is explained by the fact that IT determined from observation times shorter than the whole distribution of IT for a certain particle results in a shorter IT than the real average IT. C. albicans (mannose receptor) had the fastest ingestion process, C. neoformans opsonized with specific IgG (Fc receptor) had ingestion that was nearly as fast, and the silica particles (scavenger receptors) had the slowest ingestion process. Treatment with interferon-gamma markedly impaired the attachment process for all three types of particles (and three types of receptors) but clearly impaired the ingestion process only for silica particles (scavenger receptors).
Camner
Per
P
Division of Inhalation Toxicology, Institute of Environmental Medicine, Karolinska Institutet, SE-171 77 Stockholm, Sweden. Per.Camner@imm.ki.se
Lundborg
Margot
M
Låstbom
Lena
L
Gerde
Per
P
Gross
Norma
N
Jarstrand
Connie
C
D000818:Animals; D002176:Candida albicans; D002448:Cell Adhesion / Q000502:physiology; D002478:Cells, Cultured; D003455:Cryptococcus neoformans; D007371:Interferon-gamma / Q000494:pharmacology; D037181:Lectins, C-Type; D016676:Macrophages, Alveolar / Q000502:physiology*; D008297:Male; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011956:Receptors, Cell Surface / Q000502:physiology; D011961:Receptors, Fc / Q000502:physiology; D011971:Receptors, Immunologic / Q000502:physiology; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D011994:Recombinant Proteins / Q000494:pharmacology; D051122:Scavenger Receptors, Class B; D012822:Silicon Dioxide; D013997:Time Factors
D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D011961:Receptors, Fc; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D011994:Recombinant Proteins; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; D012822:Silicon Dioxide; D007371:Interferon-gamma