AV/7-AAD staining - weird population (Aug/21/2009 )

Hi Everyone,

I'm doing AV/7-AAD staining to measure apoptosis in response to various drug treatments in a myeloid cell line. I've attached a some representative FACS plots showing a control sample (top) and a drug treated sample (bottom) in which apoptosis is definitely occurring. I'm pretty sure that the population on the bottom right are the apoptotic cells, the stuff in the middle is schmutz, and the top population are the dead cells. Any input on this weird middle population?

Thanks!

Cells in the process of becoming necrotic?