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Activation of bovine neutrophils by Pasteurella haemolytica leukotoxin is calcium dependent
Author(s) -
OrtizCarranza O.,
Czuprynski C.J.
Publication year - 1992
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.52.5.558
Subject(s) - verapamil , calcium , extracellular , respiratory burst , biology , microbiology and biotechnology , stimulation , chemistry , biochemistry , endocrinology , organic chemistry
In this study, we used the fluorescent probe Fluo‐3 to show that an increase in cytosolic free calcium, [Ca 2+ ]i, occurred when suspensions of bovine neutrophils were incubated with sublethal concentrations of P. haemolytica leukotoxin. This increase in [Ca 2+ ]i was dependent on the concentration of leukotoxin present in the medium and, at a given concentration of leukotoxin, dependent on the external calcium concentration. The calcium channel blocker verapamil and the β‐adrenergic antagonist propranolol inhibited leukotoxin‐stimulated Ca 2+ gain, as did a neutralizing antileukotoxin monoclonal antibody. As reported previously, incubation of bovine neutrophils with partially purified leukotoxin stimulated a vigorous luminol‐dependent chemiluminescence response (LDCL). The present study shows that LDCL stimulation was dependent on the presence of extracellular calcium and was inhibited by the addition of verapamil and propranolol. These data indicate that bovine neutrophils exhibit a considerable increase in cytoplasmic free calcium when they are incubated with P. haemolytica leukotoxin in the presence of external calcium. They also provide evidence that an increased [Ca 2+ ]i is required for functional activation of the bovine neutrophil oxidative burst by P. haemolytica leukotoxin.