Ultrastructural localisation of dehydrogenases in rat thymocytes after immunisation

Abstract

The distribution and localisation of lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH) were studied using electron microscopy (EM) and cytochemical reactions in the thymus of rats 3 days afterEscherichia coli immunisation. In thymic lymphoblasts of untreated rat thymus, LDH was present mainly in the nuclear envelope, in the rough endoplasmic reticulum (RER), sometimes in the cytoplasm and in the mitochondria, whereas the SDH reaction product was evident in the nuclear envelope and in the mitochondria. In the lymphocytes the LDH and SDH reaction product was observed in some mitochondria and in small quantities in the nuclear envelope. A small amount of LDH reaction product was also present loosely distributed within the cytoplasm. In the treated rats the LDH and SDH localisation was similar to that of the untreated rats, but the amount of both reaction products was increased in the nuclear envelope. Since the lymphocytes both in treated and untreated animals showed small amounts of LDH and SDH reaction product compared to that observed in the lymphoblasts, our results show a correlation between the level of cell maturation and the distribution of LDH and SDH reaction product in the thymocytes of both treated and untreated rats. However, the increase of LDH and SDH in the nuclear envelope of thymocytes of treated animals indicates a variation of cell metabolism afterE. coli immunisation. This finding would suggest that the nuclear envelope is a probable site of enzyme synthesis.