The microanatomy of calcium stores in human neutrophils, Relationship of structure to function

As changes in cytosoiic free ca2+ play key roles in coupling responses in neutrophils, it is important to locate and identify ca2+ storage sites within these cells. Here, recent data is presented which highlights the functional link between rnicroanatomical structure and cell signailing function. Fluorescent opticai probes for cytosolic free ca2+ have been used, together with organelle specific markers. We present evidence from conventional fluorescence microscopy, together with ratiometric and confocal laser scanning fluorescence microscopy, which pin-points two celiular locations for ca2+ within the neutrophil; one within the nuclear lobes, and the other towards the ceii periphery. Knowledge of these two locations provides a clear insight into how signailing in this cell type is regulated and provides a framework for explaining how specific stimuli act to produce specific responses

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

AbstractCalcium (Ca2+) signals were monitored in individual neutrophils using ratio imaging of fura-2. In contrast to N-formyl-L-leucyl-L-phenylaianine (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 neutraphils