Abstract: ObjectiveTo explore existing state and its pathology meanings of the two component circulating immune complexes of IgG specific activing complement(IgG/C₃-TCIC)in patients with Graves'disease(GD).MethodsBy a capture EL ISA,used coat IgG anti-human C 3 for coated antibody,HRP-coat anti-human IgGfor second antibody,taking 219 cases of GD as a test group and 105 healthy individuals as a control one,IgG/C₃-TCIC were characterized in this paper to compare its positive rate between the normal and abnormal levels of serum Ig,C₃,T₃,T₄,FT₃,FT₄,TG,TM and different age, sex,and to analyse the correlation between IgG/C₃-TCIC and serum total,free,composed Ig and C₃.ResultsBoth the levels and positive rates of IgG/C₃-TCIC in GD patients were remarkably higher than those in the controls(P<0.01,0.001), its positive rates were no relations with age,sex and the levels of serum thyroxine,only notablely higher in the levels of serum IgA than those of the normal groups(P<0.05).IgG/C 3-TCIC in GD patients only correlated with the complexed IgM(r=0.173 2,P<0.05).In contrast,IgG/C 3-TCIC correlated with total,free IgM and complexed C₃(r=0.496 8,0.473 1, 0.211 3,P<0.001,0.001,0.05).ConclusionThere were specific immune disorder in patients with Graves'disease.Ig switch had an important effect on regulating the formation of IgG/C₃-TCIC.It cut a new approach to further illustrate the mechanism of the relational autoimmune diseases.