Influence of X-ray irradiation on rat thymic epithelial cells: Immunohistochemical analysis

Phenotypic changes of thymic epithelial cells (TEC) were studied in male Wistar rats subjected to X-ray irradiation (3.5 Gy). TEC subsets were identified in situ on cryostat thymic sections using streptavidin-biotin immunoperoxidase staining by RMC series of monoclonal antibodies (mAbs) and anti-keratin mAbs. During the first 2 days after irradiation (primary involution phase of the thymus) cortical as well as medullary atrophic was seen, but significant phenotypic changes, compared to control, non-irradiated animals, were found on medullary TEC only. In the primary regeneration phase (3-14 days) the recovery of the cortex occurred, while further reduction of the medulla as well as changes in TEC number and antigen expression were also seen. Therefore, X-ray irradiation caused alterations in the epithelial compartment of the thymic microenvironment due to its prominent effects on the thymocytes, as well as as a result of direct TEC damage. (author)