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Murine erythroleukemia cells (MELC) were incubated with BCNU in concentrations from 1 to 160 mu molar. The cytotoxicity was linear with concentration for 10 mu mol ar(GID15) to 40 mu molar (GID95). Incubation of MELC with BCNU induced striking morphological changes in the cell which include multinucleation and cell enlargement which appear to be linear with BCNU concentration in the range from 10 to 40 mu molar. Polykaryon formation was induced in 85% of MELC when exposed to 40 mu molar BCNU and was accompanied by marked increases in chromatin condensation and cellular fragility. The mean generation time for MELC(MGT) was increased from 14 h in control cultures to greater than 48 h in 40 mu molar BCNU. Hemoglobin synthesis in the presence of Me2SO was inhibited by 50% by exposure to 10 mu molar BCNU and to zero by exposure to 40 mu mo lar BCNU. These effects can be observed at 96 h after as little as 3 h of exposure to BCNU. The effects reported above are not reversible after washing cultures and reseeding them in fresh medium lacking BCNU. This is in contrast to cisplatin, another divalent alkylating agent in which the half-life of the crosslinks appears to be much shorter and in which washing and resuspension in fresh unsupplemented medium permits recovery of ability to replicate and to synthesize hemoglobin in the presence of Me2SO. The data supports the idea that the presence of single stranded breaks in DNA are required for induction of hemoglobin synthesis.

Acetylaminofluorene-DNA adducts (AAF-DNA) were detected in the nuclei of HeLa cells exposed to N-acetoxy-2-acetylaminofluorene (N-Ac-AAF), using an immunocytological technique and specific antibodies directed against AAF modified DNA. The proportion of cells exhibiting specific nuclear immunoreactivity was dose-dependent. The time course of disappearance of adduct specific nuclear immunoreactivity was compared with removal of N-(deoxyguanosin-8-yl)-2-acetylaminofluorene (dG-C8-AAF) and other adducts.

A serially progagated cell line (L104) was established by co-cultivation of alung adenocarcinoma (L-1) from a patient with concurrent chronic lymphocytic leukemia and XC, a non-producer rat line, known to carry the Rous sarcoma virus (RSV) genome. Karyotype of the L104 cultures revealed predominantly rat-like patterns; however, about 5% of the cells reacted with HLA antibodies and demonstrated human isozyme patterns. Electron microscopy of L104 cells revealed the presence of C-type particles budding from the cell membranes and in cytoplasmic vacuoles. Virus was not detected in any of the other normal lung, lung tumor or XC cells examined after co-cultivation with XC cells. The particles isolated from tissue culture fluids had the biochemical and biophysical characteristics common to other known mammalian C-type particles and were serologically related to the woolly monkey virus (WMV)/gibbon ape leukemia virus (GaLV) complex. Cross-hybridization between viral 3H-DNA transcripts and cellular RNAs from virus-infected cells clearly show the presence of sequences in the L104 cellular RNA related to both the GaLV/WMV group of viruses and rat viruses. Hydroxyapatite chromatography reveals however that the primate-related sequences in the viral RNA are indistinguishable from WMV in thermal elution profile. The host range of L104 virus appears to vary greatly from WMV in being xenotropic and, in the cell lines thus far tested appears, to infect only rat cells. The virus gave positive KC but negative XC assays. Inoculation of whole cells or cell-free supernatants into weaning hamster did not result in either solid tumors or leukemia. Co-cultivation of appropriate cell lines may represent an approach to the detection of latent viruses in human neoplasia.

In situ hybridization was used to detect regions of human metaphase chromosomes exhibiting complementarity with radioactively-labeled RNA isolated from RD114-virus. The region of homology, as identified by autoradiography, was confined to one D-group chromosome.