In autoimmune diseases, CD4+ T cells targeted to self- antigens multiply and attack the body's own tissues. The resulting inflammation and cell damage leads to disease such as diabetes, rheumatoid arthritis, lupus, and multiple sclerosis. Now Beckman Coulter Immunomics Operations of San Diego offers a new tool: class II iTAg™ major histocompatibility complex (MHC) tetramers, which allow researchers to quantify CD4+ T cells directed against specific antigens.

Complementing the company's existing line of class I iTAg MHC tetramers,1 the class II iTAgs consist of four HLA heavy-chain monomers, each bound to a peptide and a biotin molecule. Phycoerythrin-conjugated streptavidin binds four monomers together. The specificity of the tetramers comes from both the bound peptide and the HLA allele, which must match that of the subject. To use the iTAgs, a researcher draws whole blood, adds allele-specific tetramers carrying the peptide of interest, and then counts T cells targeted to...

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