Figure 1.

Epinephrine potently inhibits pMHC multimer-induced β₂-integrin activation on antigen-specific CD8⁺ T cells. Human whole blood cells were incubated for 5 min at 37°C in the presence of pMHC multimers (A2-NLV/PE or A2-GLC/PE) and mICAM-1. (A) Representative density plots showing the gating strategy used for defining pMHC⁺ CD8⁺ T cells. From left to right, the lymphocyte gate (on the forward scatter area [FSC-A]/side scatter area [SSC-A] plot), the FSC-A/FSC height (FSC-H) duplet exclusion, the gating of CD3⁺CD8⁺ cells, and the exclusion of CD4⁺, CD14⁺, and CD19⁺ events are shown. (B and C) CMV-specific (B) and EBV-specific (C) CD8⁺ T cells were stained with A2-NLV/PE or A2-GLC/PE multimers, respectively. Multimer binding to the TCR leads to activation of β₂-integrins (left), which was detected by staining with mICAM-1. Preincubation of the cells for 5 min with 10⁻¹⁰ M (18 pg/ml), 10⁻⁹ M (180 pg/ml), or 10⁻⁸ M (1,800 pg/ml) epinephrine partially or completely blocked the activation of the β₂-integrins. Numbers indicate the MFI of mICAM-1 binding on pMHC⁺ CD8⁺ T cells, and italic numbers in brackets indicate the frequency of mICAM-1⁺ cells among pMHC⁺ CD8⁺ T cells.