Cellular distribution of dexamethasone in rabbit spleen and lymph nodes.

The binding of tritiated dexamethasone by rabbit spleen and lymph nodes was studied in vivo by dry radioautography. The labeled glucocorticoid was found in the surface and cytoplasm of eosinophil leukocytes and in the nuclei of reticular cells, plasmocytes, endothelial cells and macrophages, but not in lymphocytes, lymphoblasts or plasmoblasts. Additional administration of excess of excess of non-radioactive dexamethasone suppressed this labeling. The findings are discussed in relation to the mechanism of action of glucocorticoids in lymphoid organs.