I am trying to get rid of mRBCs in my whole blood samples. we are sending samples for FACS, and despite my efforts, the samples are still always contaminated with RBCs.

I have used Abcam 10X RBC lysis buffer, and even Thermo mouse RBC lysis buffer, two 10min rounds according to protocol, but still the pellet looks red, and during the FACS I can see the RBCs.

Anyone has the same issues? How did you solve it? Thank you!