In vitro studies of mammalian somatic cell variation. I. Detection of H-2 phenotype in cultured mouse cell lines

The isoantigenic phenotype of the H-2 locus has been detected by isohemagglutinin absorption in a line of mouse lymphoma cells growing continuously in culture for 6 years and in two established lines of fibroblastic mouse cells growing continuously in culture for 1 year. Quantitative absorption studies suggest that the concentration of H-2 isoantigens is higher in the cultured lymphoma cells than in the other two fibroblastic cell lines.

The interaction of mammalian cells with antibodies. I

The single cell plating technique has been applied to quantitation of the reproductive killing of mammalian cells by specific antibodies. This method confirms previous demonstrations by other workers of localization of all the killing activity in the gamma-globulin fraction of specific cell antisera but not of normal sera; the need for complement for the killing action in low doses of antibody and the leakage of cell constituents attending cell killing under these conditions. In concentrations of 4 per cent or higher of heated antiserum cell killing occurs without added complement. The cell plating technique permits highly reproducible quantitation of antibody action and demonstrates antibody activity in sera diluted 1:3000. It permits demonstration of very high degrees of species specificity as shown by virtually complete absence of cross-reaction between antisera to Chinese hamster and S3 HeLa cells, respectively. Somatic cells which have been sensitized by absorption of specific antibody lose their sensitization when incubated at 37 degrees unless complement is added within 1 hour.

The rate of proflavin passage into single living cells with application to permeability studies

A technique for the measurement of the uptake rate of proflavin by the single cell in tissue culture has been developed, and the kinetics of the dye transport are discussed in terms of its physicochemical properties. Some applications of the technique to the study of permeability are given.

Succinic dehydrogenase and cytochrome oxidase activities in cell cultures

Succinic dehydrogenase and cytochrome oxidase have been assayed in permanent cell lines (HEP 1, HEP 2, and HLM), in short-term cultures of chick embryo heart cells, and in various tissues. Their activities in different cells are compared by relating them to deoxyribonucleic acid. They are very low in HEP 1, HEP 2, and HLM cells by comparison with the activities in any normal tissues examined. All the succinic dehydrogenase was shown to be located in the mitochondria of the permanent cell lines by staining with tetrazolium derivatives. Both enzymes were more active in tissues of 19-day chick embryos than in those of 11- or 14-day embryos. The increasing activities found during normal development were quickly curtailed or reversed when heart cells were grown as monolayer cultures. Digitonin-treated mitochondria produced preparations with much higher activities of cytochrome oxidase than untreated samples. Activities measured in this way were again very much lower in HEP 1, HEP 2, and HLM cells than in the normal tissues. From the derived ratio of cytochrome oxidase:succinic dehydrogenase, it was apparent that cytochrome oxidase is diminished to a greater extent than succinic dehydrogenase in both permanent cell lines and short-term cultures, by comparison with the corresponding activities in embryonic and adult tissues. The features common to the metabolism of proliferating cells in vitro and malignant cells are discussed.

Effect of endotoxin on cells and on their response to infection by polioviruses

Murphy, W. H. (The University of Michigan, Ann Arbor) and C. Wisner. Effect of endotoxin on cells and on their response to infection by polioviruses. J. Bacteriol. 83:649-662. 1962.-The effect of lipopolysaccharide on HeLa-S3, HeLa-Gey, Chang-liver, Maben, and L strain mouse fibroblasts was studied. The liminal dose of endotoxin for the human epithelial cell strains was approximately 250 mug/ml, and their order of sensitivity to endotoxin was: Chang-liver, HeLa-Gey, HeLa-S3, and Maben, the latter being the most resistant. Endotoxin at concentrations exceeding 100 mug/ml was cytotoxic to the L strain of mouse fibroblasts and caused them to markedly agglutinate. Cytotoxic response of cells to endotoxin was not characterized by cell lysis, but by distinctive nuclear changes. In an attempt to demonstrate the metabolic induction of the latent infection of cell cultures by a noncytopathic variant of poliovirus, endotoxin was added at maximal subliminal concentration to cell cultures totally, partially, or fully susceptible to virus. Endotoxin caused a slight but consistent accelerative cytopathic response of cells to infection by cytopathic poliovirus, but failed to induce cytopathic response to infection by submoderate (noncytopathic) poliovirus. Although endotoxin slightly suppressed yields of poliovirus from cells, it did not affect the plating efficiency of virus on cell monolayers.

Isolation and properties of a cell from liver characterized by lipidrich particles

A cell has been isolated from explanted rabbit liver which contains, during all phases of its growth in culture, hundreds of lipid-rich particles with a distinct limiting membrane. The cell grows logarithmically with a generation time of 19 to 20 hours and during mitosis the particles are distributed between the daughter cells. Associated with the particles is the high total lipid content of the rabbit liver cell as compared with a rat liver cell, which contains few, if any, lipid-rich particles. This difference in lipid content between the two cells is due primarily to an increase in the triglyceride fraction, in contradistinction to small differences in the polar lipid and sterol ester fractions. The lipid-rich particles have been isolated and found to contain 90 per cent triglyceride on a dry weight basis. The "genetic" factors responsible for the high concentration of lipid-rich particles and triglycerides in the rabbit liver cell require for their full expression one or more factors which are present in much higher effective concentrations in rabbit serum than in horse serum. The hypothesis is advanced that the lipid-rich particles represent a normal state of the non-structural cell lipid. A procedure is described for the quantitative isolation of the lipid of cultured cells.

Studies on cell lines developed from the tissues of patients with galactosemia

Cell lines were developed from biopsies on galactosemic and non-galactosemic patients. It was shown that one can discriminate between lines from the two types of donors by their relative growth in glucose and galactose and by their ability to oxidize galactose-1-C¹⁴. The latter method was successful in distinguishing a heterozygous cell line from the normal ones. Sensitivity of galactosemic cells to galactose was suggested by some of the experiments. The kinetics of growth were in some ways reminiscent of a similar phenomenon in the transferase mutants of E. coli, though in the human cells the effect was much less marked.