IDENTIFICATION OF CD34-BLOOD CELLS AND THEIR SUBPOPULATIONS IN PRETERM AND TERM NEONATES USING 3-COLOR FLOW-CYTOMETRY( CORD)

Three-color flow cytometry was used to identify CD34+ cord blood (CB) hematopoietic progenitors of preterm (n = 13) and term (n = 18) neonat es. The frequency of CD34+ CB cells gated on the lymphocyte fraction i n term neonates is about half the frequency of preterm neonates (mean 1.84 +/- 0.8 vs. 3.49 +/- 1.8, p < 0.005). The difference of absolute CD34+ cells between the 2 groups did not reach statistical significanc e (premature 169 +/- 161 vs. mature 108 +/- 62.6 x 10(6) cells/l). The proportion of myeloid lineage-committed CD34+ cells coexpressing the CD33 antigen in preterm neonates does not significantly differ from th at found in term neonates. However, in preterm neonates a higher fract ion of erythroid lineage committed CD34+ cells coexpresses the CD71 an tigen as compared with term neonates (mean 28.7 +/- 14.1 vs. 11.4 +/- 5.7, p < 0.001). The positive correlation between gestational age and the ratio of myeloid/erythroid lineage-specific progenitor cells (r = 0.61, n = 31, p < 0.0005) suggests gestational changes in lineage comm itment of CD34+ cells.