MICRO-ENVIRONMENTAL INFLUENCES ON THE INVIVO BEHAVIOR OF NEOPLASTIC LYMPHOCYTES

A transplantable hamster lymphocytic neoplasm of probable monoclonal derivation, induced by the oncogenic DNA SV-40, was adapted to grow in the allogeneic host either as leukemia (characterized by dissemination and poor prognosis) or as lymphoma (characterized by localization and favorable prognosis). In the present experiments, the circumstances under which neoplastic lymphocytes that are transplanted in allogeneic animals retain, lose or regain the capacity for dissemination or localization are assessed. The in vitro behavior of neoplastic lymphocytes apparently is not a stable, irreversible characteristic that is transmitted to the cell progeny. It can be altered by the organ/tissue microenvironment in which the cells proliferate. Although neoplastic cell mutation followed by host selection could be responsible for changes in cell behavior, more likely the proliferating neoplastic lymphocytes acquire reversible nonmutational phenotypic characteristics during their interaction with the host microenvironment which modify their behavior and the prognosis of the neoplastic process.