Phagocytosis by human monocytes of unopsonized particulate activators of the human alternative complement pathway: induction by cytokine.
Monocytes isolated from human blood by centrifugal elutriation exhibited little ability to ingest rabbit erythrocytes (ER), zymosan particles, or desialated sheep erythrocytes. In contrast, 85 to 95% of these cells rosetted with C3b- or C3bi-bearing sheep erythrocytes (ES) or ingested IgG-coated ES. Preincubation of the monocytes with human lymphocytes increased their ability to ingest ER. the ER phagocytosis-inducing activity was contained in the 105,000 X G supernatant of lymphocyte lysates. These supernatants increased the percentage of ingesting monocytes from 5 to 15% to 80% within 60 min. The soluble factor was found to be relatively heat stable, inactivated by trypsin, and distinct from IFN-gamma. Its m.w. is less than 13,000. It was present in B and T lymphocytes and also in U937 cells. These results suggest that the ability of human monocytes to ingest nonopsonized particulate activators of the alternative complement pathway is a cytokine-inducible property and that the effect of the cytokine on complement receptor- or Fc receptor-dependent adherence or ingestion of opsonized particles is minor.
D000818:Animals; D002448:Cell Adhesion; D002474:Cell-Free System; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003167:Complement Activation; D003170:Complement Pathway, Alternative; D004912:Erythrocytes / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007700:Kinetics; D008214:Lymphocytes / Q000276:immunology; D008222:Lymphokines / Q000502:physiology*; D016215:Macrophage-Activating Factors; D009000:Monocytes / Q000276:immunology*; D009895:Opsonin Proteins / Q000502:physiology; D010587:Phagocytosis; D011817:Rabbits; D012397:Rosette Formation; D013347:Subcellular Fractions / Q000032:analysis
D008222:Lymphokines; D016215:Macrophage-Activating Factors; D009895:Opsonin Proteins; D007371:Interferon-gamma