[Studies on rat sera immunized with solubilized thyroid microsomal antigen].

Thyroid microsomal antigen was studied using sera from rats immunized with solubilized human thyroid microsomal fraction. The methods used were gel immunodiffusion and the fluorescent antibody technique (FAT). Kidney, liver and thyroid microsomal fractions were solubilized by 0.5% Triton X-100 PBS. Rat sera immunized with solubilized thyroid microsomal fraction had a few precipitin antibodies to solubilized thyroid microsomal fraction by gel immunodiffusion. One of the precipitin lines fused in a complete immunological identity with the line of the thyroglobulin-antithyroglobulin system of rabbit serum immunized with purified human thyroglobulin. One of the precipitin lines fused in a complete immunological identity with the microsome -antimicrosome antibody system of patients' sera with autoimmune thyroid disease. A precipitin line was recognized between solubilized kidney microsomal fraction and rat sera immunized with solubilized thyroid microsomal fraction. This line and a precipitin line of thyroid microsome-antimicrosome antibody system were not identical. Studies with FAT revealed that rat sera immunized with solubilized thyroid microsomal fraction could not inhibit the binding of FITC labeled patient serum (MCHA titer, 655360) on thyroid tissue section. However, studies with FAT using viable thyroid cells revealed that rat sera immunized with solubilized thyroid microsomal fraction could completely inhibit binding of patients' antibodies on thyroid cell surface whereas rat sera immunized with solubilized kidney or liver microsomal fractions were not inhibitory. The present results revealed that: 1) Rat sera immunized with solubilized thyroid microsomal fraction had a few precipitin antibodies. 2) One was an antithyroglobulin anti-