Differential control of azurophilic and specific granule exocytosis in Sendai-virus-permeabilized rabbit neutrophils

1. Rabbit neutrophils were permeabilized by treatment with Sendai virus. This was monitored by fluorescence measurement of the formation of the adduct of deoxyribonucleic acid (DNA) with ethidium bromide. 2. On addition of Ca2+, buffered (with EGTA) in the micromolar concentration range to the permeabilized cells, secretion of beta-glucuronidase (marker of azurophilic granules) and lysozyme (marker of specific granules) occurs. Lactate dehydrogenase (cytosol marker) is retained. Half-maximal secretion of beta-glucuronidase occurs at approximately pCa 6.3; lysozyme secretion occurs at approximately pCa 6.6. 3. Secretion is dependent on the provision of nucleoside triphosphates to the permeabilized cells. There is an absolute requirement for adenosine 5'-triphosphate (ATP) for the secretion of lysozyme, but beta-glucuronidase secretion can be partly supported by other nucleoside triphosphates in the order guanosine 5'-triphosphate (GTP) greater than uridine 5'-triphosphate (UTP) = xanthosine 5'-triphosphate (XTP) greater than cytidine 5'-triphosphate (CTP). 4. Secretion from both granules is complete within 10 min of adding Ca2+ to the permeabilized cells. There is a delay before commencement of beta-glucuronidase secretion of approximately half a minute; the secretion of lysozyme has no measurable delay.