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CD4 -'fōr, -'fȯr n, often attrib a large glycoprotein that is found esp. on the surface of helper T cells, that is the receptor for HIV, and that usu. functions to facilitate recognition by helper T cell receptors of antigens complexed with molecules of a class that are found on the surface of antigen-presenting cells (as B cells and macrophages) and are the product of genes of the major histocompatibility complex
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a surface antigen on helper T-cell that is particularly important for immune resistance to viruses. It is also a receptor for the human immunodeficiency virus (HIV); progressive reduction of CD4-bearing T-cells reflects the progression of AIDS.
Medical dictionary. 2011.