Beckman CD4, 59 kDa protein on T-helper cells, binds MHC II. Found on thymocytes, monocytes; aids antibody synthesis.

Beckman The cd4 antigen is a single-chain transmembrane glycoprotein with a 59 kda molecular weight. Cd4 binds to a non-polymorphic region of mhc class ii molecules and is a co-receptor in mhc class ii restricted antigen-induced activation. Cd4 is expressed on the t "helper" lymphocytes. It is present on most thymocytes where it is frequently co-expressed with cd8. Cd4 is also expressed on all monocytes, although with a lower density than on t lymphocytes. Cd4+ t lymphocytes are active in inducing and helping the synthesis of immunoglobulins by b cells. Cd4 is a receptor for the human immunodeficiency virus type i (hiv-1) envelope protein gp120. - BCKM (Additional S&H or Hazmat Fees May Apply)