Bovine neutrophils recruited by endotoxin to a teat cistern continuously produce oxygen radicals and show increased phagocytosis and extracellular chemiluminescence.
Bovine neutrophils were harvested from a teat cistern following endotoxin infusion and were compared with blood neutrophils by measurements of chemiluminescent and phagocytic activity towards C3- and IgG-opsonized and unopsonized yeast particles. Both phagocytosis and luminol-dependent chemiluminescence elicited by all three particles were enhanced in the teat cells. The increase in the luminol-dependent chemiluminescence towards C3- and IgG-opsonized particles was due to an enhanced extracellular release of myeloperoxidase. The observed increase in phagocytosis of unopsonized yeast was shown to reflect the interaction between up-regulated CR3 receptors on the surface of the teat neutrophils and the yeast particles. A high chemiluminescent activity of the teat neutrophils in both the luminol- and lucigenin-dependent systems in the absence of a phagocytic prey indicated that the NADPH oxidase was permanently active and that myeloperoxidase was continuously released by the cells. Treatment of neutrophils with cytochalasin B showed that the chemiluminescence and phagocytosis of teat neutrophils were less sensitive to this drug than that of blood neutrophils. These results indicate that the teat neutrophils have up-regulated their receptors for IgG- and C3-opsonized and unopsonized yeast on the cell surface by the action of actin. The cells also have a permanently active NADPH oxidase dependent on the association with actin and show a higher tendency than blood neutrophils to secrete the content of their primary granules during phagocytosis.
Sandgren
C H
CH
Department of Veterinary Medical Chemistry, Swedish University of Agricultural Sciences, Uppsala Biomedical Center.
Larsson
I
I
Persson
K
K
D000199:Actins / Q000502:physiology; D000818:Animals; D002417:Cattle; D002469:Cell Separation; D004731:Endotoxins / Q000494:pharmacology*; D005110:Extracellular Space / Q000187:drug effects* / Q000378:metabolism; D005609:Free Radicals / Q000378:metabolism; D008163:Luminescent Measurements; D016177:Macrophage-1 Antigen / Q000502:physiology; D008321:Mammary Glands, Animal / Q000187:drug effects* / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D019255:NADPH Oxidases; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D009195:Peroxidase / Q000378:metabolism; D010587:Phagocytosis / Q000187:drug effects*; D012441:Saccharomyces cerevisiae / Q000276:immunology
D000199:Actins; D004731:Endotoxins; D005609:Free Radicals; D016177:Macrophage-1 Antigen; D009195:Peroxidase; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D010100:Oxygen