DEMONSTRATION THAT THIAZOLE-ORANGE-POSITIVE PLATELETS IN THE DOG ARE LESS-THAN 24 HOURS OLD

Approximately 6% of dog platelets are positive for staining with thiaz ole orange, a dye frequently used to stain ribonucleic acid. In this r eport, thiazole-orange positivity is shown to mark platelets that are less than 24 hours old. Dog platelets were derivatized in vivo with N- hydroxysuccinimido biotin such that greater than 95% of all platelets were biotinylated. Newly synthesized, nonbiotinylated platelets were t hen monitored by flow cytometry for their ability to bind thiazole ora nge. After biotinylation, the percentage of biotin-negative, thiazole- orange-positive platelets increased gradually from 0.72% at 30 minutes to 5.44% at 24 hours. These data indicate that thiazole-orange staini ng does label newly synthesized platelets. (C) 1995 by The American So ciety of Hematology.