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YP Rochon, MM Frojmovic and EL Mills
Montreal Children's Hospital Research Institute, Quebec, Canada.
Changes in the light transmission of suspensions of activated neutrophils
are widely used to measure the dynamics of neutrophil aggregation. Such
studies have suggested, for example, that aggregation is irreversible for
human newborn neutrophils but fully reversible for adult cells. We have
evaluated aggregation directly by microscopic particle counting and
compared it with changes in light transmission (delta T) and with release
from three granule subsets for neutrophils activated with
N-formyl-methionyl-leucyl-phenylalanine (FMLP). Maximal increases in %T in
response to 0.5 micromol/L FMLP were approximately 25% larger for newborn
than for adult neutrophils, and were only partially reversible by 8
minutes, while %T increases for adult neutrophils were fully reversible.
However, measurements of neutrophil aggregation using light microscopy
showed that both newborn and adult neutrophils fully deaggregated. A
further independence of delta T from aggregation was found by pretreating
adult neutrophils with cytochalasin B (5 micrograms/mL) in the presence of
0.5% gelatin, a pretreatment that blocked FMLP-induced neutrophil
aggregation while allowing large increases in %T and degranulation. In
response to FMLP, newborn neutrophils released more enzyme from each
granule subset than did adult neutrophils. Our results suggest that
cellular events associated with neutrophil activation (other than
aggregation) are implicated in light transmission responses and that these
differ for adults and newborns. These results also suggest that reports of
neutrophil aggregation should be based on direct particle counting methods
rather than on %T responses.
This article has been cited by other articles:
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| Copyright © 1990 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
