IGM MONOCLONAL-ANTIBODIES RECOGNIZING FC-ALPHA-R BUT NOT FC-GAMMA-RIII TRIGGER A RESPIRATORY BURST IN NEUTROPHILS ALTHOUGH BOTH TRIGGER AN INCREASE IN INTRACELLULAR CALCIUM LEVELS AND DEGRANULATION
Sj. Mackenzie et Ma. Kerr, IGM MONOCLONAL-ANTIBODIES RECOGNIZING FC-ALPHA-R BUT NOT FC-GAMMA-RIII TRIGGER A RESPIRATORY BURST IN NEUTROPHILS ALTHOUGH BOTH TRIGGER AN INCREASE IN INTRACELLULAR CALCIUM LEVELS AND DEGRANULATION, Biochemical journal, 306, 1995, pp. 519-523
The role of IgG receptor, Fc gamma RIII, in the triggering of neutroph
il functions has been controversial. Here we show that IgM monoclonal
antibodies, Leu 11b and 1D3, recognizing Fc gamma RIII, bind to human
neutrophils triggering an increase in intracellular calcium concentrat
ion and release of myeloperoxidase upon degranulation but do not trigg
er a respiratory burst detectable as lucigenin-enhanced chemiluminesce
nce. Although many fewer molecules of IgM monoclonal antibody, MY43, r
ecognizing Fc alpha R, bind to the same cells they trigger a much grea
ter increase in intracellular calcium concentration, release of myelop
eroxidase and a strong respiratory burst. Since the respiratory bursts
triggered by IgG and IgA are equivalent, this demonstrates that Fc ga
mma RII is responsible for the IgG-mediated response. IgM monoclonal a
ntibody MC2, recognizing the abundant neutrophil cell-surface carbohyd
rate CD15, also triggers a small rise in intracellular calcium but no
respiratory burst.