| Abstract: | A specific stimulation of tubulin tyrosinolation in human polymorphonuclear leukocytes (PMN) is induced by the synthetic peptide chemoattractant, N-formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe), and this stimulation of tyrosinolation in PMN is completely inhibited in the presence of various reducing agents. Further studies to characterize the mechanism of stimulation of tyrosinolation in PMN have revealed that conditions that inhibited the respiratory burst in stimulated PMN, e.g., an anaerobic atmosphere, or addition of antioxidants such as cysteamine, azide, or 2,3-dihydroxybenzoic acid, also inhibited the peptide-induced stimulation of tyrosinolation in these cells. Moreover, the sulfhydryl reagent, N-ethylmaleimide, depressed tyrosinolation in resting PMN and completely inhibited the fMet-Leu-Phe-induced stimulation. In contrast, addition of diamide, which preferentially oxidizes cellular glutathione, significantly stimulated tyrosinolation both in resting and fMet-Leu-Phe-stimulated PMN. Furthermore, resting levels of tyrosinolation in seven patients with chronic granulomatous disease (CGD), whose oxidative metabolism is severely depressed, were 35-45% lower (P less than 0.01). Most strikingly, PMN from CGD patients failed to respond to fMet-Leu-Phe or the Ca2+-ionophore A23187, which also induced stimulation of tyrosinolation in normal resting PMN. Methylene blue normalized the depressed tyrosinolation in resting CGD PMN, although it did not increase tyrosinolation in stimulated PMN. These results are consistent with the idea that the characteristic activation of the oxidative metabolism and the associated changes in the redox state in stimulated PMN are coupled to the induction of stimulation of tubulin tyrosinolation in these cells. |
