Analysis of Ig/Ig two-component-determined circulating immune complexes (TCIC) provide new insights into host immunity.

There have been many reports on circulating immune complexes (CIC), but information regarding Ig/Ig two-component-determined circulating immune complexes (TCIC) is not available. In the present study, we measured the levels of heterogeneous Ig/Ig two-component-determined circulating immune complexes (Ig/Ig-TCIC) in healthy individuals and patients with hepatitis A, Graves' disease and gastric cancer. The heterogeneous Ig/Ig-TCIC was dissected into IgM/IgG-TCIC, IgG/IgA-TCIC and IgA/IgM-TCIC by use of coating and detecting antibodies. The current study has been carried out in 383 cases of healthy individuals, 97 cases of hepatitis A, 108 cases of Graves' disease and 126 cases of gastric cancer. We found that changes on the levels of IgM/IgG-TCIC and IgG/IgA-TCIC is a common feature in patients studied in this study. A total of 71.4% and 80% of patients with gastric cancer had decreased IgM/IgG-TCIC and IgG/IgA-TCIC, respectively. In addition, elevated frequencies were found in patients with hepatitis A and Graves' diseases for IgM/IgG-TCIC (51.5% and 38.0%, respectively) and IgG/IgA-TCIC (29.9% and 19.4%, respectively). In summary, our results suggest that Ig/Ig-TCIC may be a hallmark for evaluation of host immunity. Decreased frequency in gastric cancer and increased frequencies in hepatitis A and Graves' disease forms a peculiar trait for detection of IgM/IgG-TCIC and IgG/IgA-TCIC. Our findings have, thus, provided new insights into circulating immune complexes.