The cytotoxic factor in thyroid disease

Diagnostic tests for thyroid antibodies: a comparison of the precipitin and latex-fixation (Hyland TAI) tests

The clinical significance of thyroid antibodies is discussed and it is concluded that, of the antibody tests which have been extensively applied, the precipitin test is the most useful for diagnostic purposes. The recently introduced Hyland TA test is compared with the precipitin test. The TA test gives a rapid result and is slightly more sensitive, but it remains undecided whether a true positive result is always indicative of clinically important degrees of chronic thyroiditis. The TA test also gives occasional false positive results, not indicative of antibody to thyroglobulin. Furthermore, approximately 12% of precipitin-positive sera from patients with Hashimoto's disease give negative TA tests, and since these also have low titres, or are negative, in the tanned red cell haemagglutination test, the precipitin test is the only simple method of demonstrating the antibody concerned. In spite of these disadvantages, the TA test is regarded as a useful procedure, and there are advantages in using both the precipitin and TA tests together for routine diagnostic purposes. A modification is described whereby the TA test reagent may be used to titrate antibody to thyroglobulin.

In vitro studies of ulcerative colitis. I. Reactions of patients' serum with human fetal colon cells in tissue cultures

By means of immunofluorescent methods it has been shown that sera from children with ulcerative colitis contain antibodies which react with fetal colon cells in tissue culture. 5 out of 13 sera from patients reacted positively when tested for staining antibodies while 12 sera from healthy individuals yielded negative results. The specificity of the staining reactions was confirmed by inhibition experiments. The staining capacity of various sera was correlated to their hemagglutinating titer when tested against phenol-water extracts of human colon. The presence of blood group substances of the ABO system on fetal colon cells in tissue culture could be demonstrated by application of fluorescent H agglutinins from eel. Cross-inhibition experiments indicated that the H agglutinins stained colon antigens which were different from those reacting with the antibodies of ulcerative colitis sera. The reactivity of cultured fetal colon cells with the antibodies in ulcerative colitis sera was retained for up to 12 days, with optimal staining at 4 to 5 days. Reactivity with H agglutinins was present for a longer period, sometimes more than 20 days. Although antigen could be shown to be present on fetal colon cells in tissue culture, exposure of the culture, in the presence of fresh guinea pig serum, to sera from patients with ulcerative colitis did not lead to any visible cytotoxic damage. In order to investigate the possible cytotoxic effect of the sera with a more sensitive technique, freshly explanted fetal colon was dispersed by trypsinization and the cells labeled with ³²P-orthophosphate. Subsequently, these cells were exposed to sera, in a final concentration of 30 per cent, from patients or healthy controls in the presence of fresh guinea pig serum (final concentration 15 per cent). Approximately 20 per cent of the cellular isotope was released into the medium within 150 minutes of incubation, but the release was the same in the samples treated either with patients' sera or normal control sera. Thus, under the present conditions, the patients' sera did not exert any specific cytotoxic action on colon cells.

Natural cytotoxicity of peripheral blood leukocytes from normal subjects and patients with Hashimoto's thyroiditis against human adult and fetal thyroid cells

Natural cytotoxicity of human peripheral blood leukocytes against fetal and adult human thyroid cells was investigated in vitro. Natural killer (NK) cell activity was determined at various effector: target cell ratios in a standard 51Cr release assay with human thyroid cells as targets. The effector cells were unfractionated peripheral blood mononuclear cells obtained by Hypaque-Ficoll gradient centrifugation. We have demonstrated that peripheral blood leukocytes from normal subjects and patients with Hashimoto's thyroiditis exhibit natural cytotoxicity against both human fetal and adult thyroid cells. This was effector: target cell ratio and incubation time dependent. Although there was a tendency for increased killing of fetal thyroid cells by peripheral blood leukocytes from patients with Hashimoto's thyroiditis compared to age/sex matched normal subjects this was not significant and there were no significant differences between the two groups for killing of adult thyroid cells. A possible role for natural cytotoxicity in progressive thyroid tissue destruction in Hashimoto's thyroiditis is discussed.

Thyroiditis: current views of pathogenesis

From indirect and circumstantial evidence it would appear that subacute thyroiditis is probably a viral infection of the thyroid gland. The thyroid may respond in the stereotyped manner to any one of a number of viruses. Despite the available evidence, however, the viral theory has yet to be finally proven. Autoimmunity does not appear to be a primary factor in the initiation of subacute thyroiditis, although transient immunologic responses occur as a secondary phenomenon. Autoimmune thyroiditis, on the other hand, is almost certainly a primary immunologic disease, and likely is due to a specific inherited defect in immunologic control. It would appear that both cell-mediated immunity and humoral immunity (i.e., T and B lymphocytes) are necessary for the full expression of this disorder.