Direct and indirect in vivo stimulation of LAF-like production induced by acute nonspecific inflammatory processes.

Peritoneal macrophages harvested from animals undergoing an acute non-immunological inflammatory reaction induced by an injection of calcium pyrophosphate ( CaPP ) or dextran into the pleural cavity showed an enhanced level of production of a lymphocyte activating factor (LAF) like material. On the other hand, macrophages harvested from the site of inflammation did not show enhanced production of this activity when compared to macrophages derived from normal controls. This enhanced activity was observed for up to two/three days after initiation of the inflammatory reaction and was obtained in both the presence and absence of lipopolysaccharide (LPS) during in vitro cultivation. Thus these results demonstrate that the acute inflammatory reaction, initiated by a non-antigenic stimulus ( CaPP ), is able to stimulate macrophages remote from the inflammatory site to produce a factor which behaves like LAF in a standard LAF assay.