Ultrastructure of Interdigitating Cells in the Rat Thymus During Cyclosporin A Treatment
Cyclosporin A (CsA) is well-known for its immunosuppressive characteristics. 1 A peculiar activity ascribed to the compound is the induction of auto-immune phenomena resembling graft-versus-host disease. This emerges in rodents after a short-course CsA treatment during the recovery phase after lethal irradiation and syngeneic bone marrow transplantation. 2 A role for the thymus has been implicated in this so-called syngeneic graft-versus-host disease. 3 Histology of the thymus after CsA treatment shows the almost absence of medullary areas. 4,5 The normal medulla is characterized by the presence of medium-sized lymphocytes with the medullary T-cell immunophenotype, and by the microenvironment consisting of medulla-type epithelium and interdigitating cells (IDC). Besides some small remnants, these components of the medulla are lacking in animals after a two-week period of CsA treatment. The disappearance of medullary epithelium and IDC has been related to a disturbance of negative selection of lymphocytes, resulting in the export of potentially autoreactive cells, that give auto-immune phenomena in the periphery.
KeywordsDaily Subcutaneous Injection Normal Thymus Birbeck Granule Medullary Area Interdigitating Cell
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- 8.E. J. de Waal, L. H. P. M. Rademakers, H.-J. Schuurman, and H. van Loveren, Interdigitating cells in the rat thymus during Cyclosporin A treatment. Ultrastructural observations, Thymus in press (1992).Google Scholar