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Image of CD4 co-receptor binding to MHC (Major Histocompatibility Complex) non-polymorphic region. In molecular biology, CD4 (cluster of differentiation 4) is a glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). CD4 is found on the surface of immune cells such as helper T cells, monocytes, macrophages, and dendritic cells.
The CD4 + /CD8 + ratio is the ratio of T helper cells (with the surface marker CD4) to cytotoxic T cells (with the surface marker CD8). Both CD4 + and CD8 + T cells contain several subsets. [1] The CD4 + /CD8 + ratio in the peripheral blood of healthy adults and mice is about 2:1, and an altered ratio can indicate diseases relating to ...
The main effector cells of T h 1 immunity are macrophages as well as CD8 T cells, IgG B cells, and IFN-γ CD4 T cells. The key T h 1 transcription factors are STAT4 and T-bet. IFN-γ secreted by CD4 T cells can activate macrophages to phagocytose and digest intracellular bacteria and protozoa.
The CD8 co-receptor is predominantly expressed on the surface of cytotoxic T cells, but can also be found on natural killer cells, cortical thymocytes, and dendritic cells. The CD8 molecule is a marker for cytotoxic T cell population. It is expressed in T cell lymphoblastic lymphoma and hypo-pigmented mycosis fungoides. [4]
Optimal CD8 + T cell response relies on CD4 + signalling. [44] CD4 + cells are useful in the initial antigenic activation of naive CD8 T cells, and sustaining memory CD8 + T cells in the aftermath of an acute infection. Therefore, activation of CD4 + T cells can be beneficial to the action of CD8 + T cells. [45] [46] [47]
All T cells derive from progenitor cells in the bone marrow, which become committed to their lineage in the thymus.All T cells begin as CD4-CD8-TCR- cells at the DN (double-negative) stage, where an individual cell will rearrange its T cell receptor genes to form a unique, functional molecule, which they, in turn, test against cells in the thymic cortex for a minimal level of interaction with ...
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 ...
Among these are the naive forms of helper T cells (CD4 +) and cytotoxic T cells (CD8 +). Naive T cells, unlike activated or memory T cells, have not encountered its cognate antigen within the periphery. After this encounter, the naive T cell is considered a mature T cell.