Quantitation of hepatic sinusoidal macrophages during the acute systemic inflammatory reaction in two animal species

The participation of hepatic sinusoidal macrophages (HSM) in hepatocyte stimulation during the acute systemic inflammatory reaction has been suggested by recent in vitro investigations. A first attempt in studying the role of these cells in vivo would appear to be the quantitation of HSM at the different times of the inflammatory response, in order to determine whether the participation of HSM depends on the recruitment of blood monocytes to the liver or on the proliferation of resident cells. HSM were counted during the initial stages (0, 16, and 24 hr) of a turpentine-induced inflammation in the rat and the rabbit. They were identified on morphological grounds and were counted separately in the periportal and the perivenous areas of the hepatic lobule. No significant differences were found in the number of HSM per field at 0, 16, and 24 hr following the induction of inflammation. No variation in the distribution of these cells within the lobule could be detected during this period. These results do not support the hypothesis that the acute phase reaction is accompanied by an influx into the liver of newly recruited macrophages or by the proliferation of resident cells. Thus, if a commitment of HSM occurs in vivo during the acute systemic inflammation, it may depend on the activation of resident cells.