Influence of a sublethal irradiation on the immune response of the mouse to sheep erythrocytes]

In the CBA mice, the immunological response of the spleen cells (RFC and PFC direct and indirect) against the sheep erythrocytes is highly depressed by a 400 R dose of X rays. The recovery is not complete at the 30th day after irradiation. The response of the bone marrow cells either irradiated or unirradiated to the antigenic stimulation is very low.     

Relative resistance of early memory cells in mice primed with sheep erythrocytes to cytotoxic effects of anti-theta serum

A series of human fetal and adult thymuses was fractionated on discontinuous gradients of bovine serum albumin. Fetal thymocytes were 10 times as mitotically active as equivalent adult cells. The predominating cell in the youngest fetus (11.0 cm CR length) was found in the less dense layers of the gradient while the predominating adult cell type was in the more dense layers. As the fetus and infant mature, there is a gradual shift from the fetal to the adult gradient profile.     

Immunogenic and adjuvant properties of rat erythrocytes subjected to exposure to a high external temperature

The erythrocytes of Wistar rats, subjected to heating at 40 degrees C (4 times, each heating lasting 40 min.) were found to be more immunogenic in mice than the erythrocytes of intact rats. The immunization of intact Wistar rats, in a single injection, with syngeneic erythrocytes obtained from the heated animals did not induce immunological response reaction, whereas 5 injections of these erythrocytes caused an increase in the number of rosette-forming cells. The injection of syngeneic erythrocytes obtained from the heated rats to intact animals also stimulated the development of immune response to sheep erythrocytes.     

Drug-induced immune tolerance to sheep erythrocytes in mice of different lines]

Immunological tolerance to sheep erythrocytes was induced in mice of the CBA, C57BL/6, CC57BR, C3H, DBA/2 lines by means of combined administration of a high dose of the antigen and cyclophosphamide. The count of 19S antibody-forming cells was determined in the mouse spleen after the test injection of erythrocytes, by local hemolysis in gel. The extent of the tolerance induced proved to depend on the genotype of the animals; mice of the DBA/2 line were found to be most "sensitive" to its induction. There was revealed no correlation between the level of the immunological reactivity to sheep erythrocytes in the intact mice of different lines and the extent of its suppression in tolerance induction     

The effects of moderately high temperature on zeaxanthin accumulation and decay

Moderately high temperature reduces photosynthetic capacities of leaves with large effects on thylakoid reactions of photosynthesis, including xanthophyll conversion in the lipid phase of the thylakoid membrane. In previous studies, we have found that leaf temperature of 40°C increased zeaxanthin accumulation in dark-adapted, intact tobacco leaves following a brief illumination, but did not change the amount of zeaxanthin in light-adatped leaves. To investigate heat effects on zeaxanthin accumulation and decay, zeaxanthin level was monitored optically in dark-adapted, intact tobacco and Arabidopsis thaliana leaves at either 23 or 40°C under 45-min illumination. Heated leaves had more zeaxanthin following 3-min light but had less or comparable amounts of zeaxanthin by the end of 45?min of illumination. Zeaxanthin accumulated faster at light initiation and decayed faster upon darkening in leaves at 40°C than leaves at 23°C, indicating that heat increased the activities of both violaxanthin de-epoxidase (VDE) and zeaxanthin epoxidase (ZE). In addition, our optical measurement demonstrated in vivo that weak light enhances zeaxanthin decay relative to darkness in intact leaves of tobacco and Arabidopsis, confirming previous observations in isolated spinach chloroplasts. However, the maximum rate of decay is similar for weak light and darkness, and we used the maximum rate of decay following darkness as a measure of the rate of ZE during steady-state light. A simulation indicated that high temperature should cause a large shift in the pH dependence of the amount of zeaxanthin in leaves because of differential effects on VDE and ZE. This allows for the reduction in ΔpH caused by heat to be offset by increased VDE activity relative to ZE.     

Stem cell, T- and B-lymphocyte migration in mouse lines that are high and low reactors to sheep erythrocytes]

Migration of stem cells and B-lymphocytes from the bone marrow and of T-lymphocytes from the thymus was studied on special models in mice of the CBA and C57BL lines, responding to sheep erythrocytes oppositely. Genetically-determined differences in the height of the immune response between the CBA and C57BL mice in immunization with sheep erythrocytes depended to a certain extent on different expression of the process of intensification of migration of the stem cells, T- and B-lymphocytes in response to the antigen administration.     

Mechanism of the effect of sera from rats subjected to high external temperature on rosette formation by splenic lymphocytes from non-immune animals]

Serum of rats subjected to the action of moderately high external temperature increased the immunogenicity of heterologous erythrocytes, but became inactive at a temperature of 2 degrees C and after the treatment with a polyvalent proteinase inhibitor--trasilol. Incubation of sheep erythrocytes with the serum of heated rats intensified the reaction of rosette formation by the lymphocytes of the spleen of intact rats. Incubation of the spleen cells with the sera of intact and heated rats failed to influence the rosette formation. After trasilol treatment the serum of heated rats completely lost the property to intensify the reaction of rosette formation. Phenomenon of intensification of rosette formation was revealed in case of treatment of erythrocytes with the sera at a temperature of 37 degrees C and was not reproduced at a temperature of 2 degrees C. Investigations carried out indicated that the increase in the immunogenicity of sheep erythrocytes and the intensification of their binding with the lymphocyte receptors of intact rats under the effect of the serum of heated animals were caused by the action of the same factor.     

Influence of high temperature on the enzyme activity of the small intestine in thyroidectomized rats]

It was revealed in acute experiments that exposure to high temperature changed the invertase, dipeptidase, lipolytic and alkaline phosphatase activity of the small intestinal mucosa in rats. The direction of these changes and their degree differed in the thyroidectomized and sham-operated animals. It is suggested that the thyroid hormones took part in the reaction of the fermentative systems of the small intestine to the action of the thermal factor.