Leukocyte and 67Ga-citrate dynamics in experimental subcutaneous Streptococcus faecalis infections

The dynamics of white blood cell (WBC) and 67Ga-citrate accumulation were studied in rabbits with subcutaneous polyethylene chambers. Uninfected chamber fluid (CF) contained less than 1,000 WBCs/mm3, most of which were mononuclear. After 67Ga injection, radioactivity increased slowly in uninfected fluid, peaked between 24 and 48 hours, and then gradually decreased. 67Ga scans showed no uptake in excess of background levels around the uninfected chambers. After injection of Streptococcus faecalis directly into the chambers, bacterial concentrations initially decreased, increased by 4-24 hours, and then decreased slightly. WBCs began to increase 4 hours after infection due to influx of polymorphonuclear leukocytes. 67Ga localized in infected chambers before the increase in WBCs. Use of the subcutaneous chamber model could help elucidate the mechanism(s) of 67Ga accumulation at sites of inflammation.