Human myelopoiesis in culture of liquid medium lacking colony stimulating factors: therapeutic implications for cancer patients with leukopenia.

Patients with cancer often develop leukopenia caused by chemotherapy. Since their treatment with human colony stimulating factors (CSFs) has limitations, it is imperative to determine if CSFs are essential in regulating human myelopoiesis. For this purpose, human primary precursor myeloid cells were cultured in media lacking exogenous human CSFs and stem cell factor (SCF), and supplemented with human sera, or with fetal bovine or other types of animal sera.

Biologic properties of viable deletion mutants of simian virus 40 (SV40) rescued from the cells of an SV40-induced hamster lymphocytic leukemia.

A lymphocytic leukemia induced by the oncogenic DNA simian virus 40 (SV40) in an inbred LSH/SsLak Syrian golden hamster was evoked to produce infectious SV40 by fusion of the leukemia cells with grivet monkey kidney (GMK) cells and by exposure of the leukemia cells to the chemical inducers mitomycin C and cycloheximide. Plaque-purified viable substrains of the rescued SV40 when studied by restriction endonuclease digestion of viral DNA were found to contain small deletions within the Hind III restriction fragment C. These deletions lay near the viral origin of DNA replication.

Microenvironmental influences on the in vivo behavior of neoplastic lymphocytes.

A transplantable hamster lymphocytic neoplasma of probable monoclonal derivation, induced by the oncogenic DNA simian virus 40, has been 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) [Diamandopoulos, G. Th. (1978) Proc.