Neutrophil cytoplasts: relationships of superoxide release and calcium
pools
M Torres and TD Coates
Activation of human polymorphonuclear neutrophils (PMNs) by the chemotactic
peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP) leads to a transient
increase in intracellular level of ionized calcium and an alteration of the
plasma membrane permeability. Calcium has been proposed as a second
messenger for activation of the PMN. Modulation of intracellular pools of
calcium is of importance in the regulation of PMN activation. We have
studied the changes in membrane-bound and cytoplasmic calcium in PMN and
PMN devoid of granules and nucleus by quantifying changes in
chlorotetracycline (CTC) and Quin 2 fluorescence and comparing their
relation to O(2) release. Similar to PMN, PMN cytoplasts (PMN-CPs) produce
equivalent amounts of O(2) in response to 10(-7) mol/L fMLP. The decrease
in CTC fluorescence following fMLP stimulation is not significantly
different in PMN-CP (-9.9% +/- 3.7%) from that observed in PMN (-12.7% +/-
2.33%), suggesting that the trigger pool of Ca++ is present in PMN-CPs.
Although PMNs show a net increase in free Ca++ as measured by Quin 2,
PMN-CPs display a lower sustained rise, which is totally abolished in the
absence of external Ca++. PMN-CPs release O(2) efficiently in the absence
of external Ca++ when stimulated with 10(-7) mol/L fMLP, whereas PMNs
release significantly less O(2) under the same conditions. Our results
suggest that a rapid rise in free Ca++, as monitored by Quin 2
fluorescence, is not required for expression of full activation of the
oxidase system and release of O(2) from PMN-CPs.
Volume 64,
Issue 4,
pp. 891-895,
10/01/1984
Copyright © 1984 by The American Society of Hematology
