The effect of accelerated release of rat neutrophil polymorphonuclear leucocytes from bone marrow on cell accumulation in inflammatory exudates.

The purpose of this study was to establish whether there was enhancement or impairment of the migratory abilities of polymorphonuclear leucocytes (PMN) released prematurely into the circulation during the inflammatory response, as a consequence of their shortened bone-marrow transit time. Sixteen healthy young adult male Sprague-Dawley rats received an i.v. injection of 1 microCi (methyl-3H) thymidine per g body wt, followed 40 h later by the i.p. injection of 2 ml of a mixture of Brain Heart Infusion/Proteose Peptone (BHI/PP). Four, 8 and 12 h after injection of BHI/PP, isotope incorporation in blood and peritoneal exudates was compared by liquid scintillation counting. During the first 12 h of the inflammatory response there was no significant difference between levels of isotope incorporation in blood and peritoneal exudates. Thus the accelerated release of cells from the bone marrow did not affect their ability to emigrate into the local lesions during this period.