CD4/CD45RA

CD4 recognizes 60Kd MW lymphocyte surface antigen identified by monoclonal antibodies belonging to the CD4 cluster and present on 54% of peripheral blood T lymphocytes, 50% of thymocytes and some malignant cells of T cell origin. Normal B lymphocytes, monocytes or granulocytes do not express surface CD4 antigen although cytoplasmic expression has been observed in monocytes/macrophages. The CD4 positive T lymphocyte subpopulation has been characterised functionally as comprising helper cells active in amplification of immune responses. CD45RA, 220 kD MW component of the Leucocyte Common Antigen complex located on some CD4+ T lymphocytes, B lymphocytes and CD8+ lymphocytes. The CD45RA+/CD4+ lymphocytes functionally exert suppressor/inducer activity in in vitro assay systems.