We recently purchased several new serologic cell washers. During validation testing, we have found that the cell button is not as "dry" as on our previous equipment from the same manufacturer (IEC). We are on our 3rd replacement of the new washer. The first one received had several drops of saline left on the cells which was absolutely unacceptable. This last replacement leaves a very small amount of saline on the red cell button, but is easily seen as different than our other washers. What is a good guideline for acceptability or definition of a good decant on the cell button?

The purpose of the cell washer is to automatically remove protein from the cells, not to produce a dry button. The automated decant cycle of all cell washers I've used will inevitably leave a small amount of saline, as will a manual decant unless you're really, really good at blotting it. I guess the question is how much is too much, and we defined it as one drop (25uL?)

A small amount of residual saline will not affect the test results. DAT testing can be performed with a 3% cell suspension, which is almost all saline in the drop you add to the tube.

Since moving to gel, we hardly ever use our cell washer anymore ...