A<unk>  (also known as a<unk>  stain) is a procedure that uses<unk> ic proteins to detect and quantify T cells that are specific for a given antigen within a blood sample. The<unk> s used in the<unk>  are made up of four major histocompatibility complex (MHC) molecules, which are found on the surface of most cells in the body. MHC molecules present peptides to T-cells as a way to communicate the presence of viruses, bacteria, cancerous mutations, or other antigens in a cell. If a T-cell's receptor matches the peptide being presented by an MHC molecule, an immune response is triggered. Thus, MHC<unk> s that are bioengineered to present a specific peptide can be used to find T-cells with receptors that match that peptide. The<unk> s are labeled with a fluorophore, allowing<unk> -bound T-cells to be analyzed with flow cytometry. Quantification and sorting of T-cells by flow cytometry enables researchers to investigate immune response to viral infection and vaccine administration as well as functionality of antigen-specific T-cells. Generally, if a person's immune system has encountered a pathogen, the individual will possess T cells with specificity toward some peptide on that pathogen. Hence, if a<unk>  stain specific for a pathogenic peptide results in a positive signal, this may indicate that the person's immune system has encountered and built a response to that pathogen.
Tetramer assay
Direct fluorescent antibody
Reverse complement polymerase chain reaction
Rabbit test
Rabbit Test
Heterophile antibody test
Ink blot test
Immunofluorescence