LEUKOCYTE RECRUITMENT AND TURNOVER IN AN EXPERIMENTAL INFLAMMATORY EXUDATE

The turn-over of leukocytes at sites of inflammation in vivo is to a l arge extent uninvestigated, mainly due to the technical difficulties a ssociated with sampling and analysis of the inflammatory exudate. This paper investigates the immigration of fluorescently labeled granulocy tes into exudate chambers at 8 h and at 1, 3, and 6 days after implant ation into abdominal muscle of rat. In each experiment, the circulatin g granulocytes were labeled by intravenous administration of the DNA-l abeling fluorochrome Hoechst 33342(R) and allowed to migrate into the chamber during 6 h before harvesting the chamber exudate. The rate of granulocyte immigration into the chamber varied considerably over time , showing a minimum at 3 days after implantation. The resulting kineti c pattern of granulocyte numbers in the exudate showed a two-step appe arance, different from that of earlier determinations in soft tissue. A comparison between the calculated rates of granulocyte immigration a nd the total number of granulocytes present in the exudate at differen t times indicated that all immigrated cells survived in the chamber fo r the entire observation period of 6 days.