A reassessment of the energy requirements for neutrophil migration: adenosine triphosphate depletion enhances chemotaxis

Abstract

In view of previous studies demonstrating a significant correlation between adenosine triphosphate (ATP) depletion and impairment of chemotaxis (CTX) during granulocyte (PMN) storage, we sought to quantitate the relationship between CTX and PMN energy metabolism. We incubated PMNs at 37 degrees C with 2-deoxyglucose (2-dg) in the presence of 5 mmol/L glucose. As expected, ATP inhibition by 2-dg was time-dependent (T 1/2, 18 minutes) and dose-dependent, with half-maximal inhibition of ATP (ID50) with 1.3 +/- .3 mmol/L 2-dg. Similar concentrations of 2-dg inhibited lactate generation, phagocytosis, superoxide anion generation, and degranulation. The random migration of PMNs was inhibited by somewhat higher concentrations of 2-dg (ID50, 12 mmol/L). In contrast, up to 40 mmol/L 2-dg did not inhibit CTX toward synthetic peptides or activated serum. In fact, 2-dg consistently increased the CTX of PMNs toward 10(-8) mol/L f-Met-Leu-Phe (fMLP), to a maximum of 450% of control CTX using 15 mmol/L 2-dg. Half-maximal stimulation (ED50) of CTX occurred at 6.3 +/- 1.0 mmol/L 2-dg. Although maximal CTX toward optimal concentrations of fMLP was consistently increased with 2-dg, the ED50 of CTX to fMLP was unchanged (ED50 with glucose, 2.0 +/- 0.6 nmol/L fMLP; ED50 with 2-dg 2.2 +/- 0.7 nmol/L fMLP), and 2-dg did not increase fMLP receptors. In the absence of glucose, 2-dg exerted similar effects on ATP and CTX, but at doses 30- to 50-fold lower than in the presence of glucose. Other glycolytic inhibitors (iodoacetamide and sodium fluoride) exerted similar effects. Additional studies indicated that CTX enhancement by 2-dg (a) required Mg++ but not Ca++, (b) occurred with PMNs from a patient with chronic granulomatous disease, (c) was unaltered in the presence of inhibitors of proteolysis, (d) was not due to generation of a soluble agent, (e) was not due to alterations in PMN adherence, and (f) was not due to inhibition of glycosylation. We conclude that the chemotaxis, but not the random migration, of PMNs is surprisingly resistant to inhibition of energy metabolism and depletion of ATP, since concentrations of 2-dg that decreased ATP and other cell functions by more than 50% not only did not inhibit, but actually stimulated, CTX. These studies also indicate that the previously reported correlation between ATP depletion and CTX impairment observed in stored PMNs are not causally related.