CD4 expression in neurons of the central nervous system

CD4 Is a member of the Ig gene super family expressed on the surface of many thymocytes and of a subset of T lymphocytes. Human CD4 is the receptor for HIV envelope glycoproteln gp120. Human and mouse CD4 transcripts are expressed in human and mouse central nervous system (CNS), but no corresponding proteins have been reported yet. We have analyzed mRNA expression and carried out Immunological experiments on adult mouse brain with probes specific for the long and short CD4 transcripts and with antibodies monospeclflc for mouse CD4. The main result of these experiments Is that the full length CD4 transcript and the CD4 protein are expressed coordinated in neurons throughout the adult mouse brain. CD4 Immunoreactlvlty Is also present in brain small vessel walls, ependymal cells, and chorold plexus. The brain mouse CD4 protein is indistinguishable from the thymua protein. In addition, we show that neuronal cells in primary cultures from human fetal CNS are Immunoreactlve to human CD4 mAbs.