Morphocytochemical reaction of the lymph nodes in dogs to the administration of lysozyme

By means of morphological, morphometrical and histochemical methods pelvic and tracheobronchial lymph nodes have been studied in dogs and concentration of lysozyme has been estimated in blood serum, in lymph and the lymph nodes after a single intramuscular injection of lysozyme (2 mg/kg of body mass). In the material investigated total concentration of lysozyme reaches its maximal values in 6 h after injection, then it gradually decreases and in 48 h reaches its control level. Morphometrically changes in cell composition are revealed predominantly of immune-competent cells in T- and B-dependent zones of the lymph nodes. Thus, the volumetric part of lymphoblasts in the germinative centers of the lymphoid nodules reaches its maximal indices by 48 h after lysozyme injection, while plasmatization of the paracortical zone and of medullary cords increases up to the 7th day. By the 14th day the volumetric part of lymphoblasts, immunoblasts and plasmocytes decreases gradually, and in 21 days after injection of the drug contents of the blast forms of the cells in the structural-functional zones of the lymph nodes does not differ from that in the control. The data obtained demonstrate the immunomorphological rearrangement of the lymph nodes in response to the exogenic lysozyme administration.     

High-dose γ-irradiation enhances the expression of a transgene controlled by the immediate-early CMV promoter in stably transfected tumor cells

γ-irradiation is commonly used to inactivate whole-cell anticancer vaccines containing viable tumor cells. To evaluate the effect of γ-irradiation on transgene expression in tumor cells, human and mouse cell lines were stably transfected with constructs expressing the granulocyte macrophage colony-stimulating factor (GM-CSF) or green fluorescent protein (GFP) gene under the control of the immediate-early CMV promoter. Irradiation of cells at 20–100 Gy caused a loss of proliferation capacity and gradual cell death, with the survival depending on the irradiation dose. G2/M cells accumulated in irradiated cultures, while the portion of S-phase cells was reduced. Surviving cells displayed activation of β-galactosidase and morphological changes associated with cell senescence. Mitochondrial dehydrogenase activity did not change with the irradiation dose. Irradiated cells retained transgene expression. Moreover, the amount of secreted GM-CSF and GFP production significantly increased after γ-irradiation, up to tenfold in cells exposed to 100 Gy. Transgene expression increased gradually and positively correlated with the total irradiation dose. The results demonstrate that γ-irradiation at 100 Gy is optimal for whole-cell anticancer vaccine inactivation.