CD4

CD4 is glycoprotein found on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic cells. It is co-receptor that assists the T-cell receptor (TCR) with antigen-presenting cell and also interacts directly with MHC class II molecules of the surface of antigenpresenting cells. Most mature T-cell lymphomas are CD4 positive with the exception of aggressive NK-cell leukemia and extranodal NK/T-cell lymphoma. CD4 plays important role in the classification of lymphocytes in inflammatory legions and malignant lymphomas.