The expression of NG2 chondroitin sulfate has been widely associated with o
ligodendrocyte precursors in rodents. We used a monoclonal antibody (9.2.27
) against the human homologue of the rat NG2 to determine whether expressio
n of this molecule was associated with a specific glial cell population pre
sent in dissociated cell preparations derived from adult and fetal human br
ain tissue. Our data, derived using FAGS and immunocytochemical analyses of
immediately ex vivo or cultured glial cells, indicate that the large major
ity of NG2 expressing cells belonged to the microglial lineage (CD68, CD11c
) rather than to the oligodendrocyte lineage (O4, A2B5, GalC). In situ immu
nohistochemistry performed on non-fixed normal spinal cord tissue confirmed
the observation that NG2 is expressed by mononuclear phagocytes of the CNS
. In contrast, peripheral blood-derived monocytes were NG2(-). Cells from f
etal brain tissue showed only small numbers of NG2(+) cells, which was cons
istent with the number of microglial cells in this preparation. In absence
of additional markers, we cannot exclude that this anti-NG2 mAb might also
recognize human oligodendrocyte progenitor cells. GLIA 27:259-268, 1999. (C
) 1999 Wiley-Liss, Inc.