Influence of methylprednisolone on reticuloendothelial phagocytic and opsonic function during traumatic and septic...

Previous studies have indicated that resistance to shock is closely related to the phagocytic activity of the reticuloendothelial system (RES). The present study examined the possibility that steroid treatment during shock might alter RES activity. RES phagocytic function was assessed by blood clearance and organ localization of gelatinized lipid colloid; opsonin activity by in vitro bioassay; serum concentration of the opsonic alpha 2-SB-glycoprotein (cold-insoluble globulin or fibronectin) by electroimmunoassay; and hepatic sinusoidal blood flow by the fractional clearance technique. Traumatic shock was induced in anesthetized male rats in a Noble-Collip drum while septic shock developed following cecal ligation and puncture. Both shock groups demonstrated depressed RE clearance function in association with diminished hepatic colloid localization and hepatic blood flow and augmented extrahepatic colloid uptake. The injection of methylprednisolone produced no further alterations in these parameters. Steroid injection resulted in enhancement of circulating opsonic activity in all groups compared to vehicle injection. The increased activity was not accompanied by increased levels of immunoreactive opsonic protein, nor could biological activity be enhanced by addition of steroid to plasma in vitro. It is suggested that the steroid acted either to preserve or to enhance the activity of the circulating protein. The relation of this finding to the suggested beneficial effects of steroids in shock remains unresolved.