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RT Parmley, CS Gilbert and LA Boxer
Department of Pediatrics, University of Texas Health Science Center, San
Antonio 78284-7810.
"Specific granule" deficiency (SGD) has been previously associated with
lactoferrin deficiency. The antimicrobial peptides termed defensins,
comprising 30% of normal primary granule proteins, have also been shown to
be markedly deficient in SGD. The present study was undertaken to correlate
these findings with ultrastructural morphometric analysis and peroxidase
cytochemistry. Peroxidase-positive, rim-stained, large, defensin-rich dense
granules, previously described as a subpopulation of azurophil or primary
granules in normal neutrophils, were markedly decreased in a patient with
SGD. Morphometric studies of peroxidase- positive granules indicated an
average peroxidase-positive granule area (all profiles) in the patient of
0.019 +/- 0.017 micron 2 (mean +/- SD, n = 941) compared to control values
from normal neutrophils of two volunteers of 0.049 +/- 0.033 micron 2 (n =
896) and 0.050 +/- 0.039 micron 2 (n = 873) (P less than 0.001 between
patient and control samples). Granule histograms showed a single peak of
small peroxidase- positive granules, whereas control samples contained more
prominent subpopulations of larger peroxidase-positive granules. The total
number of peroxidase-positive granules per 100 micron 2 of cytoplasm in the
patient was 255 +/- 124 (mean +/- SD, n = 15 cell profiles), which was
similar to control values of 266 +/- 63 and 212 +/- 109. Thus, the defensin
deficiency in SGD is associated with a decrease in size rather than number
of peroxidase-positive granules; suggesting that defensins contribute to
normal peroxidase-positive granule size and that SGD is a more global
granule deficiency than originally thought.(ABSTRACT TRUNCATED AT 250
WORDS)
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