Cultured hPBL are harvested with 0.075M KCl solution and fixed with 3:1::Methanol:Acetic Acid fixative before casting on pre-chilled slides. The slides are then stained with 4% Giemsa staining solution (made in NaH2PO4 and Na2HPO4 buffers).

I'd be much obliged if anyone can suggest any literature that state the scoring criteria for apoptotic lymphocytes.