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Interferon‐gamma modulates cytosolic free calcium in human neutrophilic granulocytes
Author(s) -
Røtnes J. S.,
Aas V.,
Iversen J. G.
Publication year - 1994
Publication title -
european journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.904
H-Index - 84
eISSN - 1600-0609
pISSN - 0902-4441
DOI - 10.1111/j.1600-0609.1994.tb01867.x
Subject(s) - calcium , flow cytometry , n formylmethionine leucyl phenylalanine , granulocyte , chemistry , priming (agriculture) , cytosol , intracellular , calcium in biology , fura 2 , interferon gamma , biophysics , microbiology and biotechnology , biochemistry , immunology , biology , neutrophile , in vitro , botany , germination , organic chemistry , enzyme
To investigate the role of cytosolic free calcium ([Ca 2+ ] i in interferon‐γ (IFN‐γ) pre‐activation (priming) of human neutrophilic granulocytes (PMN) we used three different fluorescence methods, i.e. digital imaging of single, adherent, Fura‐2 loaded cells, flow cytometric measurements of single, non‐adherent, Fluo‐3 loaded cells, and spectrofluorometry of Indo‐1 loaded PMN in suspension. IFN‐γ increased the [Ca 2+ ] i level in single, adherent PMN during the second phase of the fMLP response. The bacterial peptide fMLP (N‐formyl‐L‐methionyl‐L‐leucyl‐L‐phenylalanine) is a known stimulant of the calcium/inositol phosphate system. The [Ca 2+ ] i increase was abolished in Ca 2+ ‐free test buffer. Furthermore, the baseline [Ca 2+ ] i level was found to be slightly increased in IFN‐γ primed PMN as analysed with flow cytometry. On the other hand, these [Ca 2+ ] i responses were not detectable with the other methods used. We suggest that IFN‐γ increases the plasma membrane permeability for calcium in PMN, and substantiate this by demonstrating compliance with a capacitative model for intracellular calcium regulation. Mathematical modeling also suggested that IFN‐γ primed human PMN may sequester 13% more Ca 2+ than unprimed cells in fMLP‐insensitive intracellular stores. Thus, the Ca 2+ responses to IFN‐γ are modest and not easily detectable with some of the methods currently in use. They nevertheless explain why fMLP elicits brisker responses from PMN after IFN‐γ priming.