![\"class_II_Tetramers\"](\"https:\/\/www.caltagmedsystems.co.uk\/information\/wp-content\/uploads\/class_II_Tetramers.png\")
<\/figure>\n\n\n\nMHC tetramers are complexes of four MHC molecules, associated with a specific peptide and bound to a fluorochrome. Class II tetramers bind to a distinct population of CD4+ T cells.<\/p>\n\n\n\n
MHC class II tetramer staining is more technically challenging than class I tetramer staining. Some reasons for this include:<\/p>\n\n\n\n
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- Antigen-specific CD4+ T cells are more rare than antigen-specific CD8+ T cells<\/li>\n\n\n\n
- The affinity between the T cell receptor and MHC\/peptide complex is generally lower<\/li>\n\n\n\n
- Acquisition of 100,000-200,000 CD4+ T cells is typically required<\/li>\n\n\n\n
- Exclusion gating essential<\/li>\n\n\n\n
- T cell expansion and\/or pre-enrichment may be required<\/li>\n<\/ul>\n\n\n\n
MHC class II tetramers can be used to monitor antigen-specific CD4+ T cell expansion after vaccination (Fig. 1) or after a natural immune response against a pathogen (Fig. 2).<\/strong><\/p>\n\n\n\n
![\"classIItetramer_fig1_1\"](\"https:\/\/www.caltagmedsystems.co.uk\/information\/wp-content\/uploads\/classIItetramer_fig1_1.jpg\")
<\/a>Fig 1. Ex vivo measurement of DPB1*04:01 \/TT947-967 -specific CD4+ T cells following vaccination with Tetanus Toxoid.<\/figcaption><\/figure>\n\n\n\n ![\"\"](\"https:\/\/www.caltagmedsystems.co.uk\/information\/wp-content\/uploads\/image-280.png\")
<\/a>Fig 2. Detection of DRB1*01\/EBV-specific CD4+ T cells in whole blood.<\/figcaption><\/figure>\n\n\n\n CLIP tetramers: Negative controls in human class II tetramer assays<\/h3>\n\n\n\n
Negative tetramers are important in helping set the region or gate around antigen non-specific T cells to find the positive T cells. It would be especially effective if you are troubleshooting or intend to detect a small population of antigen-specific T cells.<\/p>\n\n\n\n
For negative control of the Human class II allele, CLIP103-117 tetramers can be used. CLIP is a partial sequence of Ii (human class II associated Invariant chain). In antigen-presenting cells, MHC class II molecules assemble in the ER with Ii. The CLIP segment of Ii binds the peptide binding groove of MHC class II molecules to protect the hydrophobic binding site. Following transport to the endosomal\/lysosomal peptide-loading compartment, Ii is proteolytically cleaved, and the remaining CLIP peptide is exchanged with other peptides in a reaction catalysed by HLA-DM. It is considered that there are no CD4+ T cells that react with CLIP103-117<\/sub> peptide.<\/p>\n\n\n\n
![\"\"](\"https:\/\/www.caltagmedsystems.co.uk\/information\/wp-content\/uploads\/image-281.png\")
<\/a><\/figure>\n\n\n\nClass II Available Alleles – Stock Tetramers:<\/h3>\n\n\n\n
Human<\/h4>\n\n\n\n