EXPRESSION OF DECAY-ACCELERATING FACTOR (CD55), MEMBRANE COFACTOR PROTEIN (CD46) AND CD59 IN THE HUMAN ASTROGLIOMA CELL-LINE, D54-MG, AND PRIMARY RAT ASTROCYTES

In this report, we have shown the expression of the complement regulat ory proteins decay-accelerating factor (DAF, CD55), membrane cofactor protein (MCP, CD46) and CD59 on human D54-MG astroglioma cells by seve ral methods, including immunofluorescence, flow cytometry and Western blotting and Northern blot analysis. These studies demonstrate that al l three proteins are structurally and antigenically similar to their c ounterparts expressed on HepG2 and SW480 cells (hepatocyte and epithel ial cell lines, respectively). D54-MG cells express mRNA for all three proteins of the appropriate size(s). The phosphatidylinositol-specifi c enzyme, PIPLC, cleaved DAF from the surface of D54-MG cells, demonst rating that DAF is linked by a glycophospholipid anchor as has been sh own for other cell types. Flow cytometry demonstrates that primary rat astrocytes also constitutively express all three regulatory proteins. These data are the first to demonstrate the expression of CD59 on ast rocytes, and the presence of all three regulatory proteins on astrocyt es suggests that regulation of complement activation in the central ne rvous system is important in neural host defense mechanisms.