Regulation and selective expression of Ly-6A/E, a lymphocyte activation molecule, in the central nervous system

The Ly-6 locus encodes a group of cell surface molecules found predominately on lymphoid cells in the mouse. These proteins share several structural and functional characteristics with Thy-1, a molecule expressed in both lymphoid and neuronal tissue. Utilizing anti-Ly-6A/E monoclonal antibodies, the present results demonstrate in situ expression of these molecules in brain tissue. The findings also indicated that these molecules are not expressed during embryonic or neonatal stages of development. Moreover, although Ly-6^b haplotype mice exhibited staining primary associated with vascular elements throughout the brain, Ly-6^a mice exhibited staining predominantly associated with white matter limited to the hippocampal and midbrain regions. Although cultured glial and neuronal cells expressed marginally detectable levels of Ly-6A/E, the majority of GFAP⁺ cells in these cultures expressed high levels of Ly-6A/E following incubation with cytokines including rIFN-gamma. In addition, northern blot analysis of RNA from enriched astrocytic cultures corroborated the induction of Ly-6A/E expression. These findings have therefore established that Ly-6 is amongst those groups of genes expressed in both brain and lymphoid tissues.