Figure 1.

In situ major histocompatibility complex (MHC) class I (MHCI) tetramer staining combined with immunohistochemistry (IHC) to detect virus-specific CD8⁺ T cells. Schematic diagram of in situ MHC tetramer (IST) combined with IHC to detect virus-specific CD8⁺ T cells in fresh, unfixed tissue sections. An MHCI tetramer consists of four biotinylated MHC-class I monomers loaded with a viral peptide (or another antigenic peptide) bound to a fluorescently labeled avidin molecule. After primary incubation with MHCI tetramers, sections are fixed and then anti-FITC antibodies are used to amplify the tetramer signal. This signal is then further amplified using Cy3-tagged anti-Rabbit IgG antibodies. Sections can be counterstained with CD3 antibodies to label T cells (blue), and CD20 antibodies to label B cells (green).