Characterization of cultured thymus tissue used for transplantation with emphasis on promiscuous expression of thyroid tissue-specific genes.

Autoimmune thyroid disease occurs in some complete DiGeorge anomaly patients after thymus transplantation. This study was designed to assess the effect of culture of thymus tissue on the expression of genes involved in the development of autoimmunity. The expression of autoimmune regulator (AIRE), thyroglobulin (TG), thyroid peroxidase (TPO), and cytokeratin RNAs was examined in thymocytes and thymus tissue on the day of thymus harvest and after 14 and 21 days of culture. Immunohistochemistry was used to evaluate the cytokeratin expression in the thymus tissue. AIRE, TG, TPO, and cytokeratin mRNAs were found in harvest-day, 14-day and 21-day cultured tissues. Levels of AIRE, TG, and cytokeratin mRNAs were mostly higher after culture compared to expression on the harvest day, likely secondary to thymocyte depletion.