Karyological characterization of WI-38 cells used in the production of vaccines

According to the valid requirements, samples of WI-38 cells taken prior to the final subcultivation for vaccine production by the manufacturer, were reconstituted, subcultivated and investigated in our control laboratories. Chromosome monitoring was done using permanent orcein stained slide preparations for direct evaluation and photographs of all selected cells for exact counts, scoring for breaks and karyotype analysis in the case of abnormalities. The tabulated summary of karyological analyses on more than 2000 cells shows that with one exception, the chromosome abnormalities did not exceed the upper limits of karyological acceptability. Photographs of abnormalities detected are presented as well as metaphases and reconstructed karyotypes. Our data are compared with those provided by the manufacturer. Obvious discrepancies in the frequency of abnormalities might be due to higher passage levels of the identical cell material tested by us and to slight differences in the methods of preparation and evaluation.