Dear Ebrahim,

if you have access to a FACS machine you can do staining for perforin in the cytotoxic T cells or looking for cleaved caspase substrates in the target cells. Another option is to use colorimetric tests for cell lysis. These are commercially available from different suppliers.

if you have a beta counter you could use 35S in order to measure cytotoxicity.

for an in vivo assay you can use luciferase positive target with/without your ag, and monitor the clearance by IVIS 

Two convenient, modern, and accepted methods for CD8+ CTL assays are usually done in tandem:  (1) LAMP-1 (CD107a) exposure.  LAMP-1 is exposed on the surface of the CTL when cytotoxic granules are released.  antibody must be incubated with the culture during the last 2h or so.  Double-stain for the killer with CD8, NK, etc.  (2) Differentially labeled (CFSEhi or CFSElo) targets co-cultured together with killers.  One contains antigen, one doesn't.  Mix the targets 50-50 before culturing with killers overnight.  Measure the change in the % of Ag+ target.   Both of these are cheap and quite easy if you have access to a flow cytometer.

Thank you very much