IDENTIFICATION AND FUNCTIONAL-CHARACTERIZATION OF THE MANNOSE RECEPTOR IN ASTROCYTES

The immune competence of astrocytes is still ill defined, especially t heir endocytic capacity, a prerequisite for efficient antigen presenta tion. We show that mannose receptor, a very important conduit for inte rnalization of infectious agents and self antigens, is functionally ex pressed in the murine CNS. By in vitro assays, astrocytes and microgli a were shown to be the prime cells expressing this receptor. Studies o n astrocytes demonstrate that its expression and function are inversel y regulated by anti-and pro-inflammatory compounds. Downregulation of the mannose receptor by IFN-gamma is concomitant with the induction of the invariant chain, which is also induced by GM-CSF + IL-4. Mannose receptor-expressing astrocytes may thus act as scavenger not only in C NS development but also in defense, against soluble and particulate ma nnosylated pathogens, presenting fragments thereof at strategic locati ons in the CNS. These findings unravel a new and putatively very impor tant role of astrocytes in innate immunity and possibly development. ( C) 1999 Wiley-Liss, Inc.