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CD8 chains contain several essential cysteine residues critical for their structural and functional roles. A disulfide bond between two cysteines in the IgV domain (C45-C115 in CD8A; C41-C116 in CD8B) is a defining feature of the immunoglobulin fold, stabilizing the two beta sheets that form this domain.
There are two isoforms of the protein, alpha and beta, each encoded by a different gene (below). CD8a: T-cell surface glycoprotein CD8 alpha chain. Identifies cytotoxic/suppressor T-cells that interact with MHC class I bearing targets CD8b: T-cell surface glycoprotein CD8 beta chain. CD9
The CD8, acting as a coreceptor, and the T-cell receptor on the T lymphocyte recognize antigen displayed by an antigen-presenting cell (APC) in the context of class I MHC molecules. The functional coreceptor is either a homodimer composed of two alpha chains, or a heterodimer composed of one alpha and one beta
Lck is anchored to the plasma membrane by associating with the co-receptor CD4 or CD8, depending on the T-cell subtype. CD4 is expressed on helper T cells and regulatory T cells, and is specific for MHC class II. CD8, on the other hand, specific for MHC class I, is expressed on cytotoxic T cells. Binding of the co-receptor to the MHC brings Lck ...
The CD nomenclature was proposed and established in the 1st International Workshop and Conference on Human Leukocyte Differentiation Antigens (HLDA), held in Paris in 1982. [4] [5] This system was intended for the classification of the many monoclonal antibodies (mAbs) generated by different laboratories around the world against epitopes on the surface molecules of leukocytes (white blood cells).
Thymocytes are classified into a number of distinct maturational stages based on the expression of cell surface markers. The earliest thymocyte stage is the double negative stage (negative for both CD4 and CD8), which more recently has been better described as Lineage-negative, and which can be divided into four substages.
Normal values (95% confidence intervals) are approximately 30-60% CD4 and 10-30% CD8 depending on age (ratio 0.9 to 3.7 in adults). [1] One reason for abnormal results is the loss of CD4-positive cells to the human immunodeficiency virus (HIV) infection. The loss of CD4-positive cells to HIV infection can result in various distortions in the ...
CD8, in contrast, functions as a dimer with either two identical alpha chains or, more typically, with an alpha and beta chain. CD8-alpha and CD8-beta each has one extracellular IgV domain in its extracellular portion. A co-receptor complex is also used by the BCR, including CD19, an IgSF molecule with two IgC2-domains.