Activation and priming of human monocytes by monocyte chemotactic activating factor: cooperation with other inflammatory cytokines and close association between an increase in cytoplasmic free Ca2+ and intracellular acidification.
Both monocyte chemotactic and activating factor (MCAF) and N-formyl-methionyl-leucyl-phenylalanine (FMLP) stimulated an increase in cytoplasmic free Ca2+ ([Ca2+]i) and changes in intracellular pH (pHi) in human monocytes in parallel at lower concentrations and stimulated superoxide (O2-) release and changes in transmembrane potential in parallel at higher concentrations. The changes in pHi were characterized by initial rapid acidification followed by sustained alkalinization, and the changes in transmembrane potential were characterized by initial depolarization followed by partial repolarization. The time courses of all responses stimulated by MCAF and FMLP were similar to each other, although the magnitude of all responses was less in MCAF-stimulated cells. MCAF by itself was a very weak stimulus for inducing O2- release. However, MCAF primed monocytes and enhanced O2- release stimulated by FMLP. The priming effect of MCAF was maximal within 5 minutes of preincubation, and the dose-response curves for priming were identical to those for triggering of an increase in [Ca2+]i. Treatment of monocytes with the intracellular Ca2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), abolished not only the increase in [Ca2+]i but also the changes in pHi (both acidification and alkalinization) induced by MCAF or FMLP. MCAF further potentiated FMLP-induced O2- release in tumor necrosis factor (TNF)-, granulocyte-macrophage colony-stimulating factor (GM-CSF)-, or IL-3-primed monocytes. These findings suggest that MCAF, alone or in concert with other cytokines, primes monocytes for enhanced release of 02-, and that MCAF- or FMLP-induced intracellular acidification and alkalinization are closely associated with an increase in [Ca2+]i, but not O2- release.
Azuma
E K
EK
Division of Hemopoiesis, Institute of Hematology, Jichi Medical School, Tochigi, Japan.
Yuo
A
A
Matsushima
T
T
Kasahara
T
T
Mizoguchi
H
H
Saito
M
M
Takaku
F
F
Kitagawa
S
S
D000328:Adult; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000494:pharmacology*; D016207:Cytokines / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D004357:Drug Synergism; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007377:Interleukin-3 / Q000494:pharmacology; D007424:Intracellular Fluid / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D009000:Monocytes / Q000187:drug effects* / Q000502:physiology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction; D013481:Superoxides / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D015220:Calcium Channels; D018932:Chemokine CCL2; D016207:Cytokines; D007377:Interleukin-3; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D004533:Egtazic Acid; D009240:N-Formylmethionine Leucyl-Phenylalanine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium