Fig. 3.
IL-18 immunoreactivity in subcellular fractions from isolated, resting human PMNs. A: immunoreactivity of a number of proteins in discrete subcellular fractions from whole cells that were sonicated. All of these control proteins are restricted to 1 subcellular fraction except for p22phox, which has a small amount of reactivity in the specific granules. C, cytosolic fraction; M, membrane fraction; G, granule fraction; MPO, myeloperoxidase; PAFr, platelet-activating factor receptor; p47phox, 47-kDa cytosolic phagocyte oxidase protein; p22phox, 22-kDa cytosolic phagocyte oxidase protein; VAMP-2, vesicle-associated membrane protein-2. In B, IL-18 immunoreactivity is restricted to the cytosolic fraction. Immunoblots are representative of 3 separate experiments; B employed 2 dissimilar antibodies to IL-18 and yielded identical results.