Serum thyroglobulin as a marker of thyroid neoplasms after childhood cancer.

AIM: To evaluate serum thyroglobulin (Tg) level as a marker of the development of thyroid disease when following individuals who received neck irradiation therapy in childhood. METHODS: In a non-randomized cross-sectional study Tg was assessed in 172 survivors of childhood cancer 10.8 y (1.9-24) median (range) after diagnosis and 7.9 y (0.9-24.3) median (range) after the end of treatment. The patients were divided into two groups: group 1 included 47 patients who had received irradiation to the neck and group 2 included 125 patients who did not receive irradiation to the neck. RESULTS: Patients who had received irradiation to the neck had significantly higher Tg levels compared with those who did not receive neck irradiation: median 14.0 (1.0-189.0) microg/L vs median 8.8, (0.7-112.2) microg/L (p < 0.001). Six out of seven patients with elevated Tg levels (>70 microg/L) had received neck irradiation. Among these six patients, two patients developed secondary differentiated thyroid cancer and two patients developed benign thyroid neoplasms. None of the patients who had normal levels of Tg developed thyroid cancer. CONCLUSION: A high Tg level should be a cause for further investigation in the follow-up of individuals who have received irradiation therapy in childhood.

Models to study the pathogenesis of thyroid autoimmunity.

In vitro and in vivo models to study the pathogenesis of thyroid autoimmunity are reviewed. Animal models with experimentally induced or spontaneously developed autoimmune thyroid disease as well as transplantation models have been used extensively in these studies, but also the use of thyroid cell cultures from both humans and animals has contributed to the present state of knowledge. Cytokines may play a role in the pathogenic mechanism in thyroid autoimmunity. The major in vitro and in vivo effects of for example interleukin-1, tumour necrosis factor and gamma-interferon on differentiated thyroid cell functions are inhibitory. The advantage of using cell cultures has been the possibility of studying an influence on thyrocytes from a single agent individually, such as cytokines, hormones or growth factors. The disadvantage is that an organism is under the influence of a multitude of factors that can only be investigated in vivo in intact organisms. Both types of models have therefore been important in the understanding of thyroid autoimmunity.

Influence of interleukin 6 on the function of secondary cultures of human thyrocytes.

Interleukin 6 has been suggested as second mediator of the effects of interleukin 1 in some cell systems. Interleukin 1 has previously been shown to inhibit the function of human thyrocytes in secondary cultures. We have therefore studied the influence of interleukin 6 (10(-1)-5.10(7) U/l) on the function of thyroid cells. Recombinant interleukin 6 slightly inhibited the production of cAMP, but failed to influence the production of thyroglobulin or the DNA content. Endotoxins (lipopolysaccharides from Salmonella abortus equi or Yersinia enterocolitica) had only a slightly inhibitory effect on thyroid cell functions, and the effect of interleukin 6 could not by itself be explained by endotoxin contamination. The effect of interleukin 6 did not mimic effects on thyroid cells afforded by recombinant interleukin 1 alpha and 1 beta. Furthermore, antibodies to interleukin 6 were not able to inhibit the interleukin 1 beta-induced inhibition of thyroid cell functions. In conclusion, it is unlikely that interleukin 6 by itself mediates the biological effects of interleukin 1 on human thyroid cells.

Interleukin-1 affects the function of cultured human thyroid cells.

Cytokines are peptide hormones essential for cellular communication in the immune response. The purpose of this study was to investigate the influence of cytokines, especially recombinant interleukin 1 beta (rIL-1 beta), on human thyroid cells. Thyroglobulin (Tg) was measured by a double antibody radioimmunoassay, and cyclic AMP (cAMP) by a competitive protein binding assay. Supernatants from unstimulated and phytohaemagglutinin-stimulated blood mononuclear cells were added to human thyroid cells cultured in monolayers. A dose-dependent inhibition of the secretion of Tg and cAMP was demonstrated. Both subcultured and primary cultured cells incubated with rIL-1 beta at pharmacological levels (10(-1)-10(2) U/ml) exhibited an inhibition of Tg and cAMP secretion, while at physiological levels (10(-5)-10(-3) U/ml), the secretion of Tg was enhanced. The similar stimulation of cAMP was demonstrated in subcultures. These in vitro studies suggest that IL-1 beta may play a role in the pathogenesis of autoimmune thyroid diseases. Further, the stimulations at low concentrations indicate that IL-1 beta may regulate the function of the thyroid gland under physiological conditions.