Synthesis and characterization of anti-idiotypic anti-T4 antibodies

Juge-Aubry CE, Liang H, Lang J, Barlow JW, Burger AG. Synthesis and characterization of anti-idiotypic anti-thyroxine antibodies. Eur J Endocrinol 1994;130:107–12. ISSN 0804–4643 We injected rabbits with purified monoclonal murine immunoglobulin (IgG1) or polyclonal anti-thyroxine antibodies (anti-T4) and polyclonal anti-triiodothyroacetic acid (anti-Triac) antibodies to stimulate the production of anti-idiotypic antibodies. Purified immunoglobulins from all five rabbits immunized with monoclonal primary antibodies were able to inhibit the interaction between [125I]T4 and the primary antibody. The preimmune sera were inactive. This effect was not due to endogenous T4 contamination or contamination with the injected primary antibody. Half-maximal inhibition of binding of primary antibody with anti-idiotype was between 1.6 and 30 μg of total immunoglobulins. Addition of normal mouse IgG1 did not alter the inhibitory effect of the anti-idiotypic antibody. suggesting that this effect is specific. These anti-idiotypic antibodies reacted differently with different polyclonal antibodies, reflecting the heterogeneous nature of polyclonal antibody populations. Polyclonal antibodies were less effective in stimulating anti-idiotypic antibody production. One polyclonal anti-T4 and one anti-Triac antibody produced weak anti-idiotypic antibody that had to be used at a concentration of > 600 μg of total immunoglobulins to be inhibitory. Both inhibited the binding of T4 to the monoclonal anti-T4 antibody. However, they were ineffective in inhibiting the function of their own antigen, the polyclonal anti-T4 or anti-Triac antibody. We tested the most potent anti-idiotypic antibodies for their ability to compete with T4 for other T4-binding proteins. Specific inhibition of T4 binding to thyroid-binding globulin was observed with half-maximal effect at approximately 450 μg of total IgG. The antibody was negative when tested against Transthyretin, rat liver deiodinase type I, triiodothyronine cell uptake and liver cytoplasmic triiodothyronine binding. In conclusion, the technique described herein allows production of anti-idiotypic anti-T4, which can be useful in the characterization of the range of iodothyronine-binding sites involved in thyroid hormone action. AG Burger, Unité de la Thyroïde, Hôpital Cantonal Universitaire, 1211 Genève 4, Switzerland