The Distribution and in Vitro Propagation of an Agent Causing High Plasma Lactic Dehydrogenase Activity

Summary

Experiments were carried out to investigate the extent of occurrence of a lactic dehydrogenase-augmenting agent in various types of tumors and its association with some known tumor-producing agents. It has been found that the agent was commonly associated with tumors which had been transplanted many times. Primary and transplanted tumors which were not exposed to exogenous sources of contamination did not show the presence of the agent. No association has been found between the agent and a variety of tumor-producing viruses. Lymphomas induced by Moloney virus showed the presence of the agent. However, tumors induced by the same virus, obtained from tissue culture, were free of the lactic dehydrogenase agent. The agent can be propagated and maintained apparently indefinitely by serial passages on primary mouse embryo tissue cultures.