Fig. 3.

‘Magic tetramers’: tetramers with mutated CD8 binding sites enable detection of CD8 T cell populations with different sensitivities. (a) CD8 null and CD8 high tetramers. (b) CD8 null tetramer has abrogated CD8 binding (through mutation D227K/T228A in the α3 domain); only high sensitivity CD8 T cells are stained. High- and low-sensitivity CD8 T cells are able to bind unmutated tetramers. CD8 high tetramers have enhanced CD8 binding (through mutation Q115E in α2 domain) and enable staining of very low sensitivity CD8 T cells.