DIFFERENTIAL EXPRESSION OF CD44 SPLICE VARIANTS IN THE NORMAL HUMAN CENTRAL-NERVOUS-SYSTEM

Cluster of differentiation 44 (CD44) is a broadly distributed group of glycoproteins that are involved in many functions related to cell-cel l and cell-matrix interactions. In the present study, the expression o f the standard form of CD44 (CD44s) and of CD44 variants (CD44v) was e xplored immunohistochemically on frozen sections of various areas of t he human CNS, The results demonstrate that CD44s epitopes are expresse d predominantly by white matter astrocytes, whereas different CD44 var iant molecules are present in neurons, on axonal membranes, on endothe lium or on choroid plexus epithelium, Interestingly, neurons and axons differentially expressed CD44 variant epitopes but consistently lack immunoreactivity for CD44s epitopes, Another interesting finding was t hat some CD44 variant epitopes expressed by neurons were localized in the cytoplasm instead of on the cell membrane. The broad distribution of variant CD44 molecules in the human CNS suggests that CD44 may play an important role in many biological processes in the CNS.