Specific binding and internalization of 111In-radiolabeled tetramers. (A) LMP₁-specificorFlu_58-66-specific CD8 cell lines were incubated with ¹¹¹In-LMP₁ tetramers or ¹¹¹In-Flu_58-66 tetramers at different concentrations on ice. Binding of ¹¹¹In-LMP₁ tetramers to LMP₁-specific CD8 T cells (•) was dose dependent. Little binding to ¹¹¹In-LMP₁ tetramers was observed when tested against the Flu-specific CD8 T cells (○). There was also little binding of the ¹¹¹In-Flu tetramers to LMP₁ CD8 T cells (▴). (B) Dose-dependent binding of ¹¹¹In-labeled LLO_91-99 tetramers to mouse LLO_91-99-specific CD8 T cells (•) and little binding to the control p60_217-225-specific CD8 T cells (○) were observed. (C) ¹¹¹In-LLO_91-99 tetramers were added to LLO_91-99-specific CD8 (left bars) or control p60_217-225-specific CD8 (right bars) T-cell lines. Cells were incubated at 37° C. Surface binding (▪) and internalization (□) of ¹¹¹In-LLO_91-99 tetramers were measured at different time points. Both cell-surface binding and internalization of ¹¹¹In-LLO_91-99 tetramers to LLO_91-99 CD8 T cells progressively increase with prolonged incubation. There was little binding or tetramer internalization with the control CD8 T-cell line (P < .0001). Data represent the mean of 2 tests from a single representive experiment that was done 3 times. Error bars indicate SEM.