[Studies on patients with a discrepancy between free thyroid hormones and thyrotropin values]

Neutralization and purification of thyroid stimulating antibody (TSAb) and thyroid blocking antibody (TBAb) by heterophilic antibody to animal IgG in Graves' disease

There are several reports that sera from Graves' patients contain heterophilic antibody (Ab) to animal IgG such as human anti-mouse antibody (HAMA). We examined the binding of TSAb and TBAb with heterophilic Ab. The binding of animal IgG with patient's IgG was examined by the inhibition of animal IgG on the binding of labeled bovine (b) IgG with patient's IgG. The binding to labeled bIgG was detected in the serum of 5 patients (2.7 %) among 185 patients with Graves' disease. The binding of the labeled bIgG with patient's IgG was inhibited by animal serum or the crude IgG (45% ammonium sulfate fraction of serum)(such as dog, horse, bovine, porcine, goat, ovine, rabbit, guinea-pig, rat, mouse) except human, monkey and chick. This heterophilic Ab which had cross-reaction with mammalian IgG (except human, monkey) was used as human anti-animal IgG Ab. TBII and TSAb activity of TSAb-positive serum, and TBII activity of TBAb-positive serum were neutralized by incubation with this Ab-bound column. Partial purification of TSAb- or TBAb- IgG from Protein A-purified TSAb- or TBAb-IgG was possible using this Ab-bound column. TBII and TSAb activity of TSAb-IgG and TBII activity of TBAb-IgG were neutralized by incubation with rabbit anti-human (h) IgG Ab (having cross-reaction with animal IgG). Further purification of Protein A-purified TSAb-IgG or TBAb-IgG by rabbit anti-hIgG Ab-bound column was impossible. The binding of TSAb and TBAb with heterophlic Ab means that TSAb-and TBAb-specific IgG have immunological similarity with mammalian species IgG compared to human IgG.