Anti-mouse CD8 clone choice is critical when mouse MHC I tetramers, as some clones, including 53-6.7, lead to high background staining of all CD8+ T cells, rather than the antigen-specific ones.
For best results, clone KT15, available from MBL International in FITC (K0227-4)is recommended. Additional information can be found in the datasheet that accompanies mouse class I tetramers, as well as the following reference containing a protocol for performing a cross titration series for optimization: Current Protocols in Immunology, MHC-Peptide tetramers to Visualize Antigen-Specific T Cells, Section 17.3.23-24, Supplement 230
