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designation for an antigen found on helper T cells; see under antigen.
a type I transmembrane protein found on helper/inducer T cells, monocytes, macrophages, and dendritic cells that is involved in T-cell recognition of antigens; expressed in mycosis fungoides, Sézary syndrome, and T-cell lymphomas.
A glycoprotein predominantly found on the surface of helper T cells. In humans, it is a receptor for HIV, enabling the virus to gain entry into its host.
(cluster designation 4) symbol for a glycoprotein expressed on the surface of helper T lymphocytes and other immune cells. CD4 serves as a receptor for human immunodeficiency virus envelope glycoprotein gp120. Binding of the viral glycoprotein gp120 to CD4 is the first step in viral entry, leading to the fusion of viral and cell membranes. CD4 count is used as an indicator of treatment timing in HIV patients.
the ratio of the number of helper T lymphocytes to the number of suppressor and cytotoxic T lymphocytes. The cells are counted with the use of monoclonal antibodies to the surface glycoproteins CD4 on helper T cells and CD8 on suppressor and cytotoxic T cells. In healthy individuals the ratio ranges from 1.6 to 2.2. The ratio is important in monitoring the function of the immune system in patients who have viral infections or who have undergone tissue transplantation, either of which may cause an increase in the number of suppressor T cells.
CD4A transmembrane glycoprotein present on T helper/inducer cells, which participates in adherence of T cells to target cells, and is involved in thymic maturation and transmission of intracellular signals during T cell activation by the class II MHC; CD4 has inducer or helper activity for T cell, B cell, and macrophage interactions, and evokes T cell proliferation in response to soluble antigens or autologous non-T cells, providing appropriate signals for B cell proliferation and differentiation into Ig-secreting cells; CD4 is also a high-affinity receptor for HIV-1's gp120, binding 42–55 of the NH2 terminal domain amino acids, and has an Ig-like fold similar to the complementarity-determining region of the kappa light chain; CD4 also binds Igs independently of the Fc receptor, and is an accessory to the T-cell receptor
A type of protein molecule in human blood that is present on the surface of 65% of human T cells. CD4 is a receptor for the HIV virus. When the HIV virus infects cells with CD4 surface proteins, it depletes the number of T cells, B cells, natural killer cells, and monocytes in the patient's blood. Most of the damage to an AIDS patient's immune system is done by the virus' destruction of CD4+ lymphocytes. CD4 is sometimes called the T4 antigen.
cluster of differentiation or cell differentiation glycoproteins.
a group of cell surface molecules which act as markers on T lymphocytes.
found on T helper (Th) and T cytotoxic (Tc) lymphocytes; associated with signal transduction.
found on T helper lymphocytes; an adhesion molecule that binds to class II MHC molecules.
found on T cytotoxic and variably on NK lymphocytes; an adhesion molecule that binds to class I MHC molecules.