Immune complexes and reticuloendothelial system function in human disease

The interrelation between the presence of circulating antigen-antibody complexes and the functional status of reticuloendothelial system Fc-receptors was studied in patients with systemic lupus erythematosus and Sjogren's syndrome. Both groups of patients had a high prevalence of circulating immune complexes as detected by the 125I-Clq binding assay and the Raji cell radioimmune assay. A number of patients with both diseases were found to have abnormal reticuloendothelial system Fc-receptor function, as measured by the clearance of IgG-sensitized, 51Cr-labeled autologous erythrocytes. In patients with systemic lupus erythematosus there was a high correlation between the presence and levels of immune complexes and abnormal clearance rates. In Sjogren's syndrome on the other hand there was no correlation between the presence or levels of immune complexes and clearance rates. In this disease patients with normal rates of clearance tended to have disease limited to exocrine glands, while patients with abnormal clearance had evidence of more widespread tissue damage. These findings are consistent with the hypothesis that defective reticuloendothelial system function may lead to the prolonged circulation of immune complexes, thereby contributing to tissue damage.