The endogenous constituents of human neutrophils that enhance the adherence of the neutrophils to surfaces have been isolated from sonicates of purified neutrophils. The predominant adherence-enhancing activity in the neutrophil sonicates cofiltered on Sephadex G-75 with a major peak of chemotactic inhibitory activity and exhibited ∼30,000 mol wt. Sequential isoelectric focusing and electrophoresis in glycerol gradients of the 30,000-mol wt activities resolved two distinct acidic protein with isoelectric points of 3.6-3.8 and 3.3-3.4 that were designated the neutrophil adherence factor (NAF) I and II, respectively. Glutamic acid and aspartic acid together accounted for a total of 18 and 19% of the amino acids in purified preparations of NAF I and NAF II, respectively, whereas the basic amino acids lysine, arginine, and histidine represented <2 and 3% of the total residues. The preincubation of portions of 2 × 106 neutrophils with as little as 6 pmol of NAF I or 9 pmol of NAF II enhanced adherence to plastic petri dishes and inhibited chemotactic migration to a maximal extent, with comparable dose-response relationships for the two effects. Neither of the NAF was cytotoxic, exhibited substantial neutrophil chemotactic or chemokinetic activity, or influenced the phagocytosis of sheep erythrocytes sensitized with immunoglobulin (Ig)G. Analyses of subcellular fractions of neutrophils indicated that the NAF are contained predominantly in the specific granules. These distinctive acidic proteins of the specific granules of human neutrophils represent a new class of endogenous constituents that may regulate the involvement of neutrophils in inflammation.
Linda K. Bockenstedt, Edward J. Goetzl
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