I performed a DAT with IgG on a cord blood sample. I washed the cells about 4 times before making 3-5% cell suspension. I washed that one drop of cells 4 times before adding IgG for DAT. The DAT result was negative.
I tried again. This time, I put two drops of unwashed cells into a tube and washed the two drops of cells 4 times before I added IgG. This time the result was M+.
What caused the differences? Do you think the washing itself can change the result?
Thanks.