[HTML][HTML] Defensin-rich granules of human neutrophils: characterization of secretory properties

M Faurschou, OE Sørensen, AH Johnsen… - … et Biophysica Acta (BBA …, 2002 - Elsevier
M Faurschou, OE Sørensen, AH Johnsen, J Askaa, N Borregaard
Biochimica et Biophysica Acta (BBA)-Molecular Cell Research, 2002Elsevier
The various granule subtypes of the human neutrophil differ in propensity for exocytosis. As
a rule, granules formed at late stages of myelopoiesis have a higher secretory potential than
granules formed in more immature myeloid cells. Neutrophils contain four closely related α-
defensins, which are stored in a subset of azurophil granules. These defensin-rich azurophil
granules (DRG) are formed later than defensin-poor azurophil granules, near the
promyelocyte/myelocyte transition. In order to characterize the secretory properties of DRG …
The various granule subtypes of the human neutrophil differ in propensity for exocytosis. As a rule, granules formed at late stages of myelopoiesis have a higher secretory potential than granules formed in more immature myeloid cells. Neutrophils contain four closely related α-defensins, which are stored in a subset of azurophil granules. These defensin-rich azurophil granules (DRG) are formed later than defensin-poor azurophil granules, near the promyelocyte/myelocyte transition. In order to characterize the secretory properties of DRG, we developed a sensitive and accurate ELISA for detection of the neutrophil α-defensins HNP 1–3. This allowed us to quantify the exocytosis of α-defensins and markers of azurophil (myeloperoxidase), specific (lactoferrin) and gelatinase (gelatinase) granules from neutrophils stimulated with different secretagogues. The release pattern of α-defensins correlated perfectly with the release of myeloperoxidase and showed no resemblance to the exocytosis of lactoferrin or gelatinase. This finding was substantiated through subcellular fractionation experiments. In conclusion, despite a distinct profile of biosynthesis, DRG are indistinguishable from defensin-poor azurophil granules with respect to exocytosis. Thus, in contrast to peroxidase-negative granules, azurophil granules display homogeneity in their availability for extracellular release.
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