New expression of myelomonocytic antigens by microglia and perivascular cells following lethal motor neuron injury.

The results of the present study demonstrate that following lethal motor neuron injury microglia and perivascular cells, as well as brain macrophages derived from the latter two cell types, newly express antigens of the myelomonocytic lineage as recognized by the monoclonal antibodies ED1 and ED3. It is suggested that differences in the immunophenotype of resident brain macrophage precursor cells, i.e. microglia and perivascular cells, and macrophages occurring outside the central nervous system (CNS) may be explained by differences in local macrophage antigen expression rather than by a different embryological lineage. The new appearance of antigens common to peripheral macrophages on neural phagocytes in CNS lesions may therefore not necessarily imply that most or all of these cells are of recent blood origin.