Effect of erythrocyte stroma on reticuloendothelial system phagocytic function

Area of Science:

• Immunology
• Hematology
• Physiology

Background:

• Intravenous administration of erythrocyte stroma is known to depress reticuloendothelial system (RES) phagocytic function.
• The mechanisms underlying this RES depression remain unclear.

Purpose of the Study:

• To investigate whether decreased hepatic blood flow, coagulation system activation, or depletion of opsonic factors mediate RES depression induced by erythrocyte stroma.
• To explore the role of impaired phagocytic cell function in stroma-induced RES depression.

Main Methods:

• Erythrocyte stroma was prepared from rat erythrocytes and injected intravenously into rats at varying doses.
• Hepatic blood flow, fibrinogen levels, fibronectin levels, and hemolytic complement levels were measured.
• RES phagocytic function was assessed using a standardized test particle.
• Experiments included heparin administration, complement depletion, and preopsonization of test particles.

Main Results:

• RES depression increased with stroma doses greater than 0.3 ml/100 gm.
• Decreased hepatic blood flow and coagulation activation were observed only at the highest stroma dose (1.0 ml/100 gm).
• Neither heparin administration nor complement depletion affected stroma-induced RES depression at a dose of 0.5 ml/100 gm.
• Preopsonization of test particles did not alter the RES depression.

Conclusions:

• Decreased hepatic blood flow, coagulation activation, and opsonin depletion do not mediate the RES depression induced by a 0.5 ml/100 gm dose of erythrocyte stroma.
• Impairment of phagocytic cell function is suggested as the primary mechanism responsible for the RES depression caused by erythrocyte debris.