Neural origin of cells in amniotic fluid.

Cells from the amniotic fluid of fetuses with open neural tube defects (NTDs) have several abnormal characteristics of potential diagnostic value. The cell number in a unit volume of fluid is 10 to 100 times the normal range of cell count. The majority of cells adhere to tissue culture dishes within 24 hours of inoculation, instead of the 4 or 5 days required by normal amniotic fluid cells. The rapidly adhering cells morphologically resemble glial cells. Their Coulter volume is about twice the average seen in normal amniotic fluid--derived cells. This larger number of oversized, rapidly adhering cells is likely due to the continuous accumulation of neural cells in the amniotic fluid. We have detected the presence of the glial protein S-100 and the absence of the neuronal protein 14-3-2 by using a specific immunofluorescence assay. We conclude that fetuses with NTDs shed large numbers of glialike cells into the amniotic fluid where their detection may have diagnostic importance.