Studies on Organ Specificity

Abstract

Summary Saline extracts of hog thyroid glands and other hog organs were prepared in as gentle a manner as possible in order to avoid denaturation of proteins and were used for immunization of rabbits. Thyroid-specific antibodies of high potency, as demonstrated by complement-fixation and precipitation techniques, could be produced by two principal methods of immunization. One method consisted of one or several courses of intravenous injection of increasing amounts of organ extract. The second method was the intradermal injection into the footpads of very small amounts of mixtures of organ extracts and Freund adjuvants. The intradermal-adjuvant method excelled the intravenous route by the amazingly small amount of extract needed for immunization and by the lack of anaphylactic or other reactions which are frequently encountered with intravenous injections. Thyroid-specific antibodies could be detected as early as two weeks after the intradermal-adjuvant injections. In addition to the antibodies against hog thyroid extract, antibodies against hog serum appeared, but were usually considerably weaker than the thyroid antibodies. Antisera obtained by the intradermal-adjuvant method frequently revealed a zone of inhibition in the area of antigen surplus, whereas antisera obtained by the intravenous route failed in most instances to show this zone. The zone of inhibition manifested itself in complement-fixation but not in precipitation tests. When tested by means of complement fixation, the tissue-specific characteristic of antisera became apparent as soon as the antigen and antiserum controls had completely cleared. However, extracts of many other organs, such as kidney, liver, heart, spleen, and others, as well as hog serum, frequently gave definite reactions. The cross-reactions disappeared on further incubation at 37°C, whereas the reaction with the homologous thyroid antigen diminished only slightly, if at all. In precipitation tests, precipitates were obtained after a short incubation time almost exclusively with the homologous antigen, while precipitation with heterologous extracts appeared only after longer standing of the extract-antiserum mixtures. The evaluation of thyroid-specific antibody functions was made by comparing antisera obtained in the same manner against the saline extracts of different hog organs or hog serum. By comparing a variety of antisera against various organ extracts the specific pattern of thyroid antisera could be established. A further way of demonstrating tissue-specific antibodies in sera obtained by immunization with hog organ extracts consisted of the removal of species-specific antibodies by absorption with hog serum. Antisera deprived of the species-specific antibodies in this manner still contained potent thyroid-specific antibodies.