THE DETERMINATION OF CELLULAR VIABILITY OF HYBRIDOMA CELLS IN MICROTITRE PLATES - A COLORIMETRIC ASSAY BASED ON NEUTRAL RED

A colorimetric assay utilising Neutral Red (C.I. 50040), a nuclear sta in, was developed to determine the cellular viability of hybridoma cel ls in microtitre plates. A linear correlation (r = 0.99) was found to exist between the uptake of Neutral Red by viable cells and the viable cell count determined by Trypan blue exclusion test. The linearity st retched over the range of cell concentrations normal in batch cultures (2-30 x 10(4)/0.2 ml) with as little as +/- 6% intra-plate well-to-we ll variation and +/- 10.2% inter-assay variation. Microscopical examin ations of viable hybridoma cells stained with Neutral Red showed that it was located in the nucleus. The possible bifunctional activity of t he Neutral Red assay as a test for cellular viability and estimating t he DNA content of hybridoma cells is discussed along with its applicat ion in a drug screening programme.