MHC Tetramers

Tetramers are multimeric peptide-MHC complexes that serve as reagents for analyzing antigen-specific T cells. The multimeric nature of tetramers increases the affinity between pMHC and TCR enabling their usage as labeling reagents for TCR. Labeling of antigen-specific T cells by tetramers makes possible the characterization of the phenotype and functionality of these cell populations, which are usually low in number.

Potential use of pMHC Tetramers

• Enumeration of antigen-specific T cells
• Characterization of antigen-specific T cells
• Isolation of antigen-specific T cells
• In situ staining of antigen-specific T cells

In the production of tetramers, the desired MHC heavy chain protein and epitopic peptide are refolded into MHC complex with 2-microglobulin in vitro. The successful refolded monomers are purified by gel-filtration and biotinylated. Tetramerization is achieved by binding to streptavidin, a fluorescent dye often added by using fluorochrome-conjugated streptavidin.

The Immune Monitoring resource can produce pMHC monomers and tetramers with defined MHC alleles and epitopic peptides.

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Currently, we have 2 mouse and 22 human alleles available for tetramer production (Table 1). Tetramers for other species are also available. Contact the resource for more information. We offer tetramers conjugated with PE, APC, AlexaFluor 647 and Qdot.

Table 1. Available MHC Class-I alleles for tetramer production

Human				Mouse
A*0101 A*0201 A*0201a A*0301 A*1101 A*2301 A*24021 A*2501 A*3002 A*3101 A*68012	B*0702 B*0801 B*1402 B*1501 B*1801 B*3501 B*4001 B*4402 B*5101 B*5201	Cw*0101 Cw*0701 Cw*0702 Cw*1203	HLA-E HLA-F HLA-G	H-2D(b) H-2K(b)

a. This allele is also available with the CD8 binding mutation.

Note
Individual tetramers can differ significantly in refolding, stability and staining of T cells. The differences are determined largely by the HLA alleles and the binding affinity of the specific peptide to the HLA molecule. We recommend the testing of each new batch of tetramers with positive and negative control cells and by titration of the tetramer reagent. Tetramers should be stored at 4°C and retested after long-term storage. Please visit the NIH Tetramer Core Facility's website for more information.