Synchronous free Ca2+ changes in individual neutrophils stimulated by leukotriene B4

Calcium (Ca2+) signals were monitored in individual neutrophils using ratio imaging of fura-2. In contrast to N-formyl-L-leucyl-L-phenylalanine (f-met-leu-phe), which produced grossly asynchronous Ca2+ signals with delays in response (up to 60 s), leukotriene B4 (LTB4) provoked synchronous and immediate elevations in cytosolic free Ca2+. Some individual neutrophils which responded immediately to LTB4, subsequently displayed delayed Ca2+ signals in response to f-met-leu-phe. A sub-population of neutrophils failed to respond to both LTB4 and f-met-leu-phe. The asynchrony of the Ca2+ signalling to f-met-leu-phe is not, therefore, an obligatory property of signal transduction in neutrophils.