Graded responses of human neutrophils induced by serum-treated zymosan
JC Whitin, DH Ryan and HJ Cohen
A modified zymosan preparation was used to probe the interaction of
particulate stimuli with human neutrophils (PMNs). After extraction with
alkali and detergent, the zymosan particles retained their ability to be
opsonized in serum and to stimulate PMNs. Serum-treated zymosan (STZ)
induced dose-dependent superoxide (O2-) production and membrane potential
depolarization in the range of 1 to 10 mg/mL of STZ. The rate and extent of
secretion of lysozyme and beta-glucuronidase were also dose-dependent in
the range of 1 to 10 mg/mL of STZ. Cytochemical studies using nitroblue
tetrazolium, however, showed that 92% of PMNs were stimulated to produce
O2- at 0.1 mg/mL of STZ. The dose response of O2- production induced by STZ
is therefore due to increasing O2- production by individual PMNs and not to
the stimulation of more PMNs to produce O2-. Evidence for O2- production
was found only in the area of PMN-zymosan contact, suggesting a mechanism
for the graded responses of PMNs treated with particulate stimuli. In order
to determine the nature of the dose dependence of depolarization (a measure
of PMN activation), PMNs equilibrated with the fluorescent probe 3,3'-
dipentyloxacarbocyanine were analyzed by flow cytometry. The results
demonstrate that STZ induces a dose-dependent depolarization of the
membrane potential of individual PMNs. These results also demonstrate that
increasing concentrations of STZ can induce increasing PMN responses even
when all of the PMNs have been activated. These results are consistent with
the hypothesis that receptor-mediated particulate stimulation of PMNs is a
phenomenon that results in graded PMN responses.
Volume 66,
Issue 5,
pp. 1182-1188,
11/01/1985
Copyright © 1985 by The American Society of Hematology
