Role of lymphocytes in dogs experimentally re-challenged with canine transmissible sarcoma.

The role of lymphocytes in dogs re-challenged with canine transmissible sarcoma (CTS) was investigated histologically and immunologically. Tumors were detected on the 3rd day, began to regress on the 9th day and disappeared on approximately the 15th day after the secondary transplantation (AST). The CTS cells were surrounded by lymphocytes which had infiltrated from the early stage, degenerated and ultimately disappeared. Most of the lymphocytes expressed thymocyte antigen (Ta) on the cell membrane surface. The numbers of lymphocytes and Ta-positive lymphocytes in peripheral blood increased gradually AST. The blastogenic responses of peripheral blood lymphocytes (PBL) induced by 3 kinds of mitogens were elevated strikingly from the early stage AST. These results suggest that Ta-positive lymphocytes play an important role in vivo in the regression of tumors and that the immunological activity of PBL is stimulated immediately AST.

Experimental transmission of enzootic bovine leukosis to sheep: latency period of the tumoral disease.

In the field of viral oncogenesis the latency period is the interval between detectable establishment of infection and appearance of a tumor. Between 1969 and 1985, a total of 60 sheep died with lymphosarcoma. They were inoculated with BLV-positive blood from various donor cows, by various routes, at various ages, etc. A statistical analysis was performed trying to find a correlation between the length of the latency period and, on the other hand, one or more factors, such as sex, family lineage, identity of the dam, age at inoculation, route of inoculation, or origin of the inoculum. None of the above mentioned parameters has a significant effect on the length of the latency period. In two series of sheep inoculated with decreasing number of lymphocytes from BLV-positive donor cows, hematological disorders and tumors appeared at first in recipient animals inoculated with the higher doses of infectious blood. Thus, the inoculated dose has an effect upon the length of the latency period; the higher the dose inoculated, the shorter the latency period. This finding suggests an explanation to the natural occurrence of multiple case herds as opposed to no-tumor case herds. A multiple case herd fulfills two conditions: the presence of a good donor and an efficient route of transmission allowing the transfer to the recipient of the optimal amount of infected blood.

Canine transmissible venereal sarcoma: electron microscopic changes with time after transplantation.

The structure of canine transmissible venereal sarcoma (CTVS) has been examined from 14 to 71 days after implantation. During early growth, the tumour appears to be composed primarily of loosely arranged, round cells and a few fibroblast-like cells. As the tumour mass increases, the round cells become tightly packed with highly interdigitating plasma membranes. The number of irregularly shaped round cells and fibroblast-like cells increases with increasing tumour mass. Collagen and reticular fibres can be found in early tumours, frequently in association with the round cells, and in regions devoid of fibroblast-like cells. During tumour regression, cellular degradation is evident in fibroblast-like and irregularly shaped cells as well as round cells. The data suggest that transformation may occur in the course of tumour growth, causing morphological change from round to fibroblast-like cells, and that CTVS is an undifferentiated round-cell sarcoma capable of differentiation in a fibroblastic direction. Also present, primarily in tumour cells from newborn dogs, are cytoplasmic lamellar arrays and crystalline virus-like structures, both previously described in other forms of tumor cells.

[Induction of subcutaneous sarcomas in the progeny of Syrian golden hamsters after treatment with Adenovirus 12 during pregnancy (author's transl)]. / Entstehung von subcutanen Sarkomen bei Nachkommen von syrischen Goldhamstern nach Behandlung mit Adeno 12 Virus während der Schwangerschaft

Subcutaneous polymorphic sarcomas were induced in 8 out 27 offspring of syrian golden Hamsters after treatment of pregnant mother animals at day 15 of gestation with Adenovirus 12. This is the first example of tumor induction in the progeny at prenatal exposure by oncogenic viruses.

[Sarcomas in syrian hamster, induced by an oncorna virus and cellfree transmissible (author's transl)]. / Durch ein Oncornavirus induzierte, zellfrei übertragbare Sarkome des Goldhamsters

1. Application of hamster papova virus to newborns of Syrian hamster has produced some s.c. sarcomas after a 5 to 6 month latency period, by virtue of the strong inducer effect of this papova virus to endogenous (latent) oncorna viruses. 2. Cellfree filtrates from a polymorphorus-cell sarcoma produced in this way, when applied to newborn hamsters of the spontaneously tumour-free hamster line HaP, again lead to sarcoma formation after a latency period of 3--8 months in about 20% of the animals; the same holds for cellfree filtrates of these cellfree induced sarcomas and their transplantation generations. 3. In these tumours C-type oncorna viruses, but no papova virus, could be demonstrated regularly. 4. The hamster specificity of this sarcoma virus is suggested by the complete absence of a tumorigenic effect of the cellfree filtrates from these hamster sarcomas in mice and rats. The preferential induction of hamster sarcomas by sarcoma filtrates, in conjunction with the fact that filtrates from hamster leukoses, indicates a certain difference between hamster leukemia and hamster sarcoma viruses.

[Morphological studies on cellfree induced sarcomas in syrian hamster (author's transl)]. / Morphologische Untersuchungen an zellfrei induzierten Sarkomen beim Goldhamster

Morphological studies on sarcomas induced in syrian hamsters by cellfree transmission are described. The tumour tissue for the cellfree preparations stemmed from a sarcoma, containing C-particles. Basically, three histological groups have been distinguished: 1. neoplasms of the peripheral nerve-sheath, 2. undifferentiated sarcomas, and 3. liposarcomas. Furthermore, a rhabdomyosarcoma, an angiosarcoma and, in a heterotransfection on rat, an osteosarcoma have been established. The great majority of tumours could be transmitted by cellfree preparations. To this neoplasms belong the undifferentiated histological structure.