A functional comparison of IIIindium-labelled elicited peripheral blood neutrophils and peritoneal neutrophils in the rat.

A functional comparison between elicited peripheral blood neutrophils has been made in vivo and in vitro. Preliminary experiments showed that separation of peripheral blood cells on a metrizamide gradient yielded too few neutrophils for efficient radiolabelling with indium (In): hence a mixed cell preparation comprising 80% neutrophils was elicited in the peripheral blood of adult male rats by the administration of endotoxin (0.25 mg i.a.) and cobra venom factor (200 microliter i.p.) 20 h before. Peritoneal neutrophils were collected 4 h after the i.p. injection of 6 ml thioglycollate. Both populations differed markedly from normal peripheral neutrophils on the in vitro testing of random locomotion, chemotaxis and phagocytosis of Candida. After labelling with IIIIn-tropolonate, a greater proportion (mean = 8%) of peripheral blood cells localized to an E. coli/Freund's complete adjuvant-induced abscess compared with peritoneal neutrophils (mean = 3%). The abscess could be visualized externally by scanning with both cell preparations, but the distribution of activity differed markedly. The greater hepatic sequestration of peritoneal neutrophils suggested cell damage or activation. To overcome the difficulty of harvesting normal peripheral blood neutrophils in the rat, either of these populations can be used to follow the kinetics of inflammation. However, elicited peripheral blood cells yield a higher proportion of responding cells.