Assaying the granulocyte-macrophage colony-stimulating factor (GM-CSP) as a mitogen of immature cells in fetal blood cultures

Based on the presence of immature cells in fetal blood? and in an attempt t o shorten the cytogenetic reporting time, three simultaneous one-day cultur e regimes were established in 23 fetal blood samples: (a) the standard phyt ohemagglutinin (PHA)-stimulated lymphocytes culture, (b) a culture using th e granulocyte-macrophage colony-stimulating factor (GM-CSF) as an alternati ve mitogen, and (c) an unstimulated culture. Diagnostic success rates achie ved by these three methods were as follows: 43 per cent (95 per cent CI: 23 -64) (GM-CSF), 30 per cent (95 per cent CI: 12-49) (PHA) and 9 per cent (un stimulated). These three regimes were also assayed in three-day cultures gi ving 100 per cent diagnostic success rate for the PHA and GM-CSF, and 62 pe r cent (95 per cent CI: 41-83) for the unstimulated. A moderate correlation was found between the initial concentration of cultured erythroblasts and the metaphase count in one-day GM-CSF-stimulated (r= 0 43, p=0.01) and unst imulated (r=0.35, p=0.05) cultures, suggesting that erythroblasts may be in part responsible for the mitotic index observed in these two regime cultur es. In conclusion, our experience suggests that immature cells in fetal blo od may be successfully cultured for diagnostic purposes. Copyright (C) 1999 John Wiley & Sons, Ltd.