INHIBITION OF SOME FUNCTIONS OF POLYMORPHONUCLEAR LEUKOCYTES BY INVITRO ZINC

  • 1 January 1977
    • journal article
    • research article
    • Vol. 89  (1) , 135-146
Abstract
In granulocytes isolated by dextran sedimentation from dog blood, the O2 consumption, phagocytosis of yeast particles, and Escherichia coli killing were tested in Tris-buffered saline medium with additions of Zn2+, Mg2+, and other divalent cations and in the presence or absence of plasma. Zn2+ inhibited all 3 cell functions in a concentration-related manner only in the presence of 1.2 mM Mg2+. Without Mg2+ in the medium the lower concentrations of Zn2+ (17-67 .mu.M) were stimulatory; 83 .mu.M Zn2+ concentration was inhibitory. A close association was found between the inhibitory effect of Zn2+ and the actual content of Zn in the cell. The uptake of Zn from the medium was minimal during the 1st min, where no Zn2+ effect on cell functions was manifest. When Zn-loaded cells with inhibited activity were washed and reincubated for at least 15 min in Zn-free medium, almost 95% of the Zn was washed out and cell activity was normalized; this indicated reversibility of the Zn effect. In the presence of increasing concentrations of autologous plasma in the medium, the effect of Zn was proportionally less pronounced and at the same time uptake of Zn by cells was decreased. Of the 6 divalent cations studied at 50 .mu.M concentration and in the presence of Mg2+, only Zn2+ was inhibitory, Se and Co were inactive, and Mn and Cu stimulated O2 consumption of latex-activated granulocytes. Zn ions, in the presence of Mg2+ in the medium, apparently inhibit various functions of dog peripheral granulocytes and this effect is closely associated with Zn uptake by the cells. The effect is reversible and specific for this metal.