Hi Florence,

I have used Trypan blue (Invitrogen) to count NK-92 cells. It gives a viable count between 75-85%, as these cells do not reach very high viability of 90% and above. Alternatively, you can also use fixable aqua live/dead dye from Invitrogen, which also works for me.

Hope this helps!

Best,

Shalini

Hello Florence,

Assessing the viability of a NK92 cell culture can be challenging, especially when the cells form clumps. One of the most reliable and accurate methods for determining cell viability is flow cytometry using a combination of dyes such as trypan blue, propidium iodide (PI), and acridine orange (AO).

Trypan blue is a commonly used dye to assess cell viability, as it enters only dead cells and stains them blue. PI is another dye that can be used to assess cell viability as it only enters cells with a damaged membrane, which is a sign of cell death. AO is another viable option, it's a live cell marker that binds to the DNA of live cells and emits green fluorescence.

The results you have obtained using the different methods are variable and unreliable, this could be due to the fact that clumping of cells can affect the accuracy of cell counting by the manual methods you have mentioned. Flow cytometry can overcome this problem as it allows for the analysis of individual cells, and can differentiate between live, dead, and clumped cells.

It is also important to note that when working with a live cell count, it is essential to maintain the cells under optimal culture conditions, such as proper temperature and humidity, adequate CO2 levels and fresh media, to ensure the highest possible viability.

In summary, flow cytometry is the most reliable and accurate method for assessing cell viability in NK92 cell culture, especially when cells are clumped. Using a combination of dyes such as trypan blue, propidium iodide and acridine orange, can increase the accuracy of the results