Effect of corticosteroids and adult thymectomy on induction and recall of contact sensitivity in mice

The effect of cortisone acetate on specific cell mediated immunity in mice was investigated using contact sensitivity to oxazolone. A long-acting cortisone acetate preparation was found to be much more effective than a soluble preparation in suppressing temporarily the recall response to oxazolone. The long-acting preparation was also effective in inhibiting the induction of sensitivity when injected before (but not after) oxazolone.

Removal of the thymus either before or after sensitization did not significantly enhance the effects of cortisone acetate, and it is therefore suggested that cortisone acetate acts independently of the thymus-derived lymphocyte population.

     

Effect of thymectomy on induction of immunologic tolerance in adult mice and on restoration of original immunoreactivity

Removal of the thymus strengthened and prolonged tolerance to sheep's red blood cells obtained with the aid of cyclophosphamide if thymectomy was performed on the mice before or after the induction of tolerance. Thymectomy had its greatest effect if performed 24 h before the induction of tolerance. The results confirm the view that this form of tolerance is due to a deficiency of a definite clone of T helpers.Laboratory of Immunologic Tolerance, N. F. Gamaleya Institute of Epidemiology and Microbiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR P. A. Vershilova.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 12, pp. 707–709, December, 1978.     

Variations in polyoma virus genotype in relation to tumor induction in mice. Characterization of wild type strains with widely differing tumor profiles.

The authors have explored the effects of variations in mouse polyoma virus genotype on patterns of tumor formation in the mouse. Four "wild type" virus strains were surveyed. Two were highly oncogenic, inducing multiple tumors of epithelial and mesenchymal origin, at high frequency and with short latency. The other two strains were weakly oncogenic, inducing fewer tumors, solely of mesenchymal origin, and after a long latency. These sharply contrasting tumor profiles were reproduced with virus stocks derived from molecularly cloned viral genomes. Though vastly different in their oncogenic properties, these cloned viruses proved equally effective in transforming established rat fibroblasts in culture and showed the same patterns of tumor antigen expression in cultured mouse cells. Complexes of polyoma middle T antigen and pp60c-src were demonstrated in extracts of epithelial tumors induced by a highly oncogenic virus strain. It is concluded that polyoma viral genetic determinants for tumor induction in the mouse are more complex than those previously defined by the use of cell transformation systems.     

Effect of neonatal thymectomy on experimental autoimmune hepatitis in mice.

Using an autoimmune hepatitis model of A/J mice which was prepared with immunization by syngeneic crude liver proteins, various influences of neonatal thymectomy were studied by observations of histological liver changes, autoantibody to liver-specific membrane lipoprotein (LSP), delayed-type hypersensitivity (DTH) to LSP, and purified protein derivative (PPD), and suppressor activity to LSP. The liver changes in the thymectomized mice were more intense than those in the non-thymectomized controls. Production of the anti-LSP autoantibodies and positive DTH to syngeneic LSP could be recognized in both groups of the thymectomized mice and the non-thymectomized controls, but the levels of those were higher in the former. In the level of DTH to PPD the thymectomized mice were lower than the non-thymectomized controls. Adoptive transfer experiments showed that suppressor activity to LSP was reduced in the spleen cells of neonatally thymectomized mice. This experiment suggests that neonatal thymectomy is apt to abolish tolerance to LSP on account of depressed suppressor activity to autoantigen, and accordingly liver damage is increased.     

Effect of thymectomy and antilymphocyte serum on Mycobacterium leprae infection in mice.

BALB/c mice thymectomized at 3 to 5 days of age were studied to determine if this procedure would result in enhanced susceptibility to infection with Mycobacterium leprae and, if so, whether or not administration of antilymphocyte serum would further increase this susceptibility. The plateau for growth in the footpads of intact mice occurred 4 months after inoculation, whereas in the thymectomized and thymetocomized plus antilymphocyte serum-treated groups the plateau occurred between months 11 and 12 after inoculation. Thymectomy resulted in at least a 10-fold increase in the number of M. leprae found in the footpads. Antilymphocyte serum did not appear to further enhance the M. leprae infection in the thymectomized mice. Although growth of M. leprae in the testes of both intact and thymectomized mice was erratic, the number of organisms reached a higher ceiling in the thymectomized groups. M. leprae harvested from all groups was passaged into intact mice at various intervals after inoculation to test for viability. Viable M. leprae were found at all intervals tested including 22 months after infection in the intact mice, suggesting that a chronic infection occurred that probably lasted during the entire life of the animals.     

Effect of interferon on induction of S antigen by polyoma virus in BHK 21 cells.

A new surface antigen (S antigen) can be detected by immunofluorescence during the abortive transformation of hamster cells by polyoma virus. It was found that addition of interferon greatly reduces the percentage of cells positive for S antigen.     

Influence of environmental enrichment on an object recognition task in CF1 mice

Environmental enrichment (EE) is an experimental model for studying neuroplasticity. EE is used to investigate behavioral modifications associated with gene-environmental interaction. The object recognition task (ORT) evaluates animals' ability to learn about their environment, which depends on their innate instinct. By using young CF1 mice, the present study evaluated the effect of 8 weeks of EE on the ORT. Our results indicate that EE decreased the time the animals spent exploring familiar and unfamiliar objects and total time spent exploring both objects, without affecting the capacity of discrimination of objects. These findings indicate a more propitious behavior for species survival in animals subjected to EE, including rapid exploration and learning about the environment.     

Transplacental transmission of polyoma virus in mice.

When pregnant mice were inoculated on day 1 of gestation with polyoma, some of them exhibited total resorption or reduced litter size, the extent depending on the dose of virus. Virus was detected in 4 out of 11 mouse embryo fibroblast (MEF) cultures made from infected mothers. After maternal infection on day 5 or 10 of gestation, virus titers of up to 10(7) 50% tissue culture infectious doses (TCID50)/g of fetus were found in all pools of fetuses tested 5 days later, with the titers falling by day 6. Hemagglutination-inhibiting antibodies against polyoma appeared in maternal serum by day 6 and rose to a maximum by day 14. Immunoglobulin G class antibodies were detected by day 7, with titers rising rapidly to a maximum at day 14. After maternal infection later in gestation (day 15), one out of three litters of newborn mice was found to have 10(5) TCID50 polyoma virus per g in pooled kidney samples.     

Effect of early thymectomy on growth of transplanted mammary gland tumors arising in C3Hf mice

Mammary gland tumors arising in factorless C3Hf mice, if transplanted into MTV-S⁺ and MTV-S^– recipients, were found to grow at the same rate and early thymectomy likewise had no effect on their growth. The more rapid growth of transplanted tumors in MTV-S⁺ than in MTV-S^– recipients after transplantation of mammary gland tumors from C3H/He mice and the inhibition of tumor growth after early thymectomy are evidently connected with special features of the immunological reaction to virus-induced antigens.Institute of Cytology and Genetics, Academy of Sciences of the USSR, Siberian Branch, Novosibirsk. (Presented by Academician of the Academy of Medical Sciences of the USSR V. P. Kaznacheev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 6, pp. 721–723, June, 1976.