CD4 cell count, a measure of the number of “helper” T cells that carry the CD4 glycoprotein on their cell surface and that help B cells produce certain antibodies. The human immunodeficiency virus (HIV) binds to CD4 and kills T cells bearing this glycoprotein. Thus, the CD4 cell count is an indicator of the progress of an HIV infection and helps measure the effectiveness of anti-HIV drugs. CD4 T cells mainly produce interleukin 2, an autocrine and paracrine T cell growth factor; preactivated or memory CD4 T cells secrete a much larger array of lymphokines on restimulation. See also CD4, CD8 cell, human immunodeficiency virus, T cell.
