Activation of transcription factor NF-kappa B by phagocytic stimuli in human neutrophils. 
Phagocytosis represents an important physiological trigger for the inducible expression of several genes in human neutrophils. Here, we report that a DNA-binding activity primarily consisting of the classical NF-kappa B heterodimer, p50/RelA, is induced in phagocytosing neutrophils. Under these conditions, NF-kappa B activation was found to be a rapid and transient response, reaching a maximum by 10-15 min, and returning to near-basal levels by 30 min. In neutrophils undergoing the phagocytosis of opsonized yeasts, the onset of NF-kappa B activation was paralleled by a decline in immunoreactive I kappa B-alpha protein levels, and the cellular I kappa B-alpha pool was replenished by 30 min, in agreement with our gel shift data. We conclude that NF-kappa B activation could constitute one of the mechanisms whereby the expression of kappa B-responsive genes is enhanced in phagocytosing neutrophils. To our knowledge, this represents the first demonstration that phagocytic stimuli can induce NF-kappa B activation in human neutrophils.