Studies on Organ Specificity

Abstract

Summary Saline extracts prepared from the thyroid glands of rabbits injected into the footpads with rabbit thyroid extract plus Freund adjuvants contain considerably smaller amounts of thyroid antigen than do identically prepared extracts from thyroid glands of normal rabbits. There seems to be some correlation between the titer of circulating antibodies and the decrease in antigen content. The reduction in specific thyroid antigen content can be demonstrated best by complement fixation tests but it can be confirmed by precipitation tests using in both instances a rabbit antiserum containing a potent rabbit thyroid antibody as a reagent. It is possible to coat erythrocytes modified by diluted tannic acid with rabbit thyroid extract. Extracts of the thyroid glands of immunized rabbits inhibit the agglutination of tanned cells coated with thyroid extract to a lesser degree than do normal thyroid extracts. Results obtained with this hemagglutination-inhibition test run parallel to those obtained by direct complement fixation and precipitiation tests. Immersion of the crude thyroid extracts in a boiling water bath for 2 min considerably increases the extent of agglutination of tanned red blood cells coated with thyroid extract by rabbit thyroid antiserum. Histologic examination of thyroid glands from rabbits treated with rabbit thyroid extract injected together with Freund adjuvants, in the manner described, revealed considerable changes. There was partial replacement of the thyroid tissue by cellular elements. The extent of the changes seen histologically again exhibits a certain relationship to the titer of circulating antibody against rabbit thyroid extract. The maximum changes observed were seen in rabbits with the highest antibody titer in contrast to less marked changes with rabbits of low antibody titer.