Edit page | Page history | Printable version

Cd4

(Science: immunology) 55-kD glycoproteins originally defined as differentiation antigens on t-lymphocytes, but also found on other cells including monocytes/macrophages. Cd4 antigens are members of the immunoglobulin supergene family and are implicated as associative recognition elements in mhc (major histocompatibility complex) class II-restricted immune responses. On t-lymphocytes they define the helper/inducer subset. Cd4 antigens also serve as hiv receptors, binding directly to the envelope protein gp120 on hiv.

The protein structure on the surface of a human cell that allows hiv to attach, enter, and thus infect a cell. Cd4 receptors are present on cd4 cells (helper T-cells), macrophages and dendritic cells, among others. Normally, cd4 acts as an accessory molecule, forming part of larger structures (such as the T-cell receptor) through which Tcells and other cells signal each other.