Abstract
The correlation between the platelet-associated IgG (PAIgG) level and the circulating immune complexes (CIC) level were studied in patients with systemic lupus erythematosus, liver cirrhosis, idiopathic portal hypertension, aplastic anemia and various types of leukemia, showing elevation of CIC. PAIgG was measured by micro-enzyme linked immunosorbent assay (mELISA), and CIC measured by three separate methods, Clq mELISA, Fc receptor (FcR) mELISA and anti-C3 (AC3) mELISA. PAIgG was elevated in 65% of the patients with the various disorders mentioned above, and CIC were elevated in 25%, 36% and 23% of patients as measured by Clq, FcR and AC3 mELISA, respectively. A weak correlation was demonstrated only between the PAIgG level and CIC level determined by Clq mELISA, while no correlations were demonstrated between the PAIgG level and the CIC level determined by the other two methods. These findings suggest the mechanism of increased PAIgG in these disorders is not explained simply by the binding of CIC to platelets via the Fc receptor. The possibilities should be also considered including the binding of antiplatelet autoantibodies to platelets or non-specific adhering of plasma proteins due to CIC mediated platelet-membrane alterations.
