ABSTRACT
BACKGROUND: Thymic epithelial cells often form lymphoid-epithelial cell (LEC) complexes, thought to contribute both to normal T-cell differentiation and to leukemogenesis. The distribution of the nerve growth factor (NGF) and NGF immunoreactivity modulation of complex-forming thymus epithelial cells were studied in mice with experimental acute L1210 leukemia. MATERIALS AND METHODS: Light and electron microscopic methods and cell separation techniques were applied. RESULTS: Immunoperoxidase and immunogold labelling showed subcapsular and subseptal overexpression of NGF by epithelial cells in leukemic thymus. NGF immunopositive epithelial cells were closely associated with lymphoid cells. The increased immunoreactivity of epithelial cells correlated with LEC complex formation, including thymic nurse cell-like structures and rosettes in the external cortex. CONCLUSION: These results provide new structural and immunocytochemical evidence for intimate contact between NGF-producing epithelial cells and lymphoid cells and suggest that NGF immunoreactive LEC complexes are involved in thymic microenvironmental reorganization during leukemogenesis.
Subject(s)
Leukemia L1210/metabolism , Leukemia, Lymphoid/metabolism , Nerve Growth Factor/metabolism , Thymus Gland/metabolism , Animals , Biomarkers, Tumor/metabolism , Cell Separation , Epithelial Cells/metabolism , Epithelial Cells/ultrastructure , Female , Immunoenzyme Techniques , Immunohistochemistry , Leukemia L1210/pathology , Leukemia, Lymphoid/pathology , Male , Mice , Mice, Inbred DBA , Microscopy, Electron, Transmission , Organelles/ultrastructure , Thymus Gland/pathologyABSTRACT
The authors examined the fine structure of the epithelial cells, obtained from the cortico-medullary transition in the thymus of 4-months conventional mice Swiss, killed by decapitation. Apart from dark and bright epithelial cells, which formed cellular reticulum of the whole thymic lobule, they described three types of epithelial cells, characteristic of this area. These cells differed mainly by the character of their vascular components, whose richness and variety was combined with other cytologic signs of increased functional activity, manifested at various degree. The obtained results widened the picture of the cortico-medullary transition as an area, independently formed in other breeds of animals with data of a thymus similar to that of a mouse and were morphologic proof for the significance of its epithelial reticulum in the functional activity of the thymus.
