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A viral immunodepressive factor associated with experimental mouse tumors
An immunodepressive factor (IDF) capable of inhibiting the rejection of allogeneic lymphomas in mice was detected in a number of transplantable mouse tumors. The allograft reactivity of the host was impaired for at least 10 months after IDF administration. No clinical evidence of bacterial or viral infection was detected in IDF-treated animals. Sera collected from mice at various intervals after injection of IDF showed a great increase in the IDF-titer. The IDF persisted in mouse sera for at least 3 months, whereas no IDF activity was found in sera of rats given injections of the factor. IDF was capable of replicating in vitro in mouse embryo cells, but not in rat embryo or HeLa cell cultures. IDF was inactivated in vitro by heat (65 degrees for 30 min), ultraviolet light or ether, but not by ethyl alcohol. These studies indicate that IDF is a virus capable of producing a long-lasting asymptomatic infection specifically interfering with the host's allograft reactivity. In several instances a close association between the lactic dehydrogenase virus and IDF was found. Nevertheless no conclusion was reached on the identity or nonidentity between the two viruses.
An immunodepressive factor (IDF) capable of inhibiting the rejection of allogeneic lymphomas in mice was detected in a number of transplantable mouse tumors. The allograft reactivity of the host was impaired for at least 10 months after IDF administration. No clinical evidence of bacterial or viral infection was detected in IDF-treated animals. Sera collected from mice at various intervals after injection of IDF showed a great increase in the IDF-titer. The IDF persisted in mouse sera for at least 3 months, whereas no IDF activity was found in sera of rats given injections of the factor. IDF was capable of replicating in vitro in mouse embryo cells, but not in rat embryo or HeLa cell cultures. IDF was inactivated in vitro by heat (65 degrees for 30 min), ultraviolet light or ether, but not by ethyl alcohol. These studies indicate that IDF is a virus capable of producing a long-lasting asymptomatic infection specifically interfering with the host's allograft reactivity. In several instances a close association between the lactic dehydrogenase virus and IDF was found. Nevertheless no conclusion was reached on the identity or nonidentity between the two viruses.