Effect of erythrocyte stroma on reticuloendothelial system phagocytic function

Previous studies have demonstrated that intravenous administration of erythrocyte stroma is followed by a depression of RES phagocytic function. The present study evaluated the possibility that depression of hepatic blood flow, activation of the coagulation system, or depletion of opsonic factors mediates the RES depression induced by erythrocyte stroma. Stroma was prepared from washed rat erythrocytes and injected into rats at doses of 0.3, 0.5, 0.75, and 1.0 ml/100 gm. RES depression increased progressively after stroma doses greater than 0.3 ml/100 gm. Hepatic blood flow was decreased only after the 1.0 ml/100 gm dose. Fibrinogen levels were decreased with the 1.0 ml/100 gm dose but were unchanged with the 0.5 ml/100 gm dose of stroma, and the RES depression induced by the 0.5 ml/100 gm dose was not modified by the administration of heparin. Circulating fibronectin levels were not consistently depressed after stroma injection, and in vitro incubation of stroma with serum did not affect fibronectin levels. Erythrocyte stroma decreased hemolytic complement levels but depletion of complement with purified cobra venom factor did not depress RES phagocytic function. Preopsonization of the RES test particle did not modify the stroma-induced RES depression. These results indicate that decreased hepatic blood flow, activation of the coagulation system, or depletion of opsonins did not contribute to the RES depression induced by the 0.5 ml/100 gm dose of stroma. These results suggest that impairment of phagocytic cell function may mediate the effect of erythrocyte debris on RES phagocytic function.