Phenotypic variability of cultured rat hepatoma cell population in respect to alpha-fetoprotein synthesis.

McA-RH 7777 hepatoma cells were cloned on 2 occasions a week apart (test cloning). Alpha-fetoprotein (AFP) phenotypes of primary and secondary clones from 55 primary clones were estimated. High interclonal heterogeneity of AFP expression was demonstrated. This variability exceeded by several orders of magnitude the mutation rate. We also found intraclonal differences in rates of variability. A "stabilizing" cloning was also carried out, aiming at the selection of AFP+ and AFP- stable cell lines. Stabilizing cloning included 7 cycles of cloning and selection of the most phenotypically stable clone. This stability was shown to be incomplete during the maintenance of clones in culture.

[Intraclonal variability in the McA-RH 7777 hepatoma cell line detected by analytical cloning]. / Vnutriklonal'naia izmenchivost' v kletochnoi linii gepatomy McA-RH 7777, vyiavlemaia analiziruiushchim klonirovaniem.

McA-RH 7777 hepatoma cell line has been cloned twice at a week's interval (analytical cloning). Alpha-fetoprotein (AFP) phenotypes of primary and secondary clones from 46 primary clones were analyzed. High interclonal variability exceeded the mutation rate by several orders. The interclonal differences have been also found in the variability rates.

[Detection and isolation of antibody-forming clones by means of local cytolysis in gel]. / Vyiavlenie i vydelenie antiteloobrazuiushchikh klonov metodom lokal'nogo tsitoliza v gele.

A method is suggested combining the screening and cloning of hybridomas producing cytotoxic antibodies. The method is based on the Erne local hemolysis principles. The cells from the preformed hybridoma line NATF 9.9 secreted monoclonal antibodies (McAb) against murine T lymphocyte differentiation antigen Lyt-3.2. A mixture of hybridoma cells and target cells was attached to the plastic Petri dish surface pretreated with Poly-L-lysine and covered with agarose. McAb production by hybridoma cells was elicited by complement-dependent lysis of target cells. The lysis was detected by incorporation in dead cells of the fluorescent dye ethidium bromide. Subsequent studies made it possible to evaluate the clonogenic capacity of McAb production and isolate active clones.