MuLV gp 70, also designated as AH1 (SPSYVYHQF), is an endogenous viral envelope glycoprotein encoded in the mouse genome that is transcriptionally silent in normal tissues. The expression of gp70 is reactivated in a few cancer cell lines including CT26 colorectal cancer and B16 melanoma cells. Other investigators have demonstrated the presence of MuLV-encoded molecules in murine lymphomas and leukemias as well as Simian Virus 40 (SV40)-transformed NIH-3T3 cells. Researchers measure total T cell and T cell subset by detection of various cell surface molecules to gain better insight into the central role of the immune system. MBL International offers MHC tetramer reagents for murine model antigens, tumor antigens, viral antigens, etc. MHC-peptide tetramer complexes detect antigen specific T-cells at the single cell level, allowing for accurate measurements of the functional immune response in cancer, infectious diseases, and automimmune diseases.
Identification and enumeration of CD8+ antigen specific T cells requires cognate recognition of the T cell receptor (TCR) by a class I MHC/peptide complex which are composed of a complex of four H-2 MHC class I molecules each bound to the specific peptide and conjugated with a fluorescent-labeled Streptavidin. Thus, MHC tetramer assays allow quantitation of the total T cell population specific for a given peptide complexed in a particular MHC molecule. Furthermore, since binding does not depend on functional pathways, this population includes all specific CD8+ T cells regardless of functional status. Measurements can be performed in whole blood or isolated lymphocyte/splenocyte or thymocyte cell preparations. Specific cell staining is accomplished by incubating the sample with the MHC tetramer reagent, then washing away excess tetramer. The number of tetramer positive lymphocytes is then determined by flow cytometry.
MuLV GP70 tetramer (TB-M521-1) reagent comprises murine class I MHC H-2Ld and epitope peptide from the envelope protein (gp70) of an endogenous ecotropic murine leukemia virus (MuLV emv-1), and it can detect an H-2Ld -restricted MuLV gp70-specific CD8+ T cells. This tetramer reagent can help preclinical validation of cancer immunotherapies. A tetramer, which is constructed with the same allele (H-2Ld ) of interest and an irrelevant peptide, may be used as a negative control Tetramer. Alternatively, a cell population devoid of Tetramer-positive cells may be used as negative control.