Immunophenotypic and functional characterization of CD33(+)CD34(+) cells in human cord blood of preterm neonates

Objective. To characterize CD33(+)CD34(+) cells, a major population in huma n cord blood (CB) CD34(+) cells of preterm neonates, Materials and methods. The proportion of CD33(+) cells nas analyzed on CB C D34(+) cells from preterm and full-term neonates, CD33(+)CD34(+) cells were purified by cell sorting and analyzed on their clonogenic activity, prolif erative activity in short-time liquid suspension culture, and GATA-2 mRNA e xpression by RT-PCR and Southern blot, Results. The absolute numbers and proportion of CD34(+) cells in mononuclea r cells inversely correlated with gestational age. CD33 was expressed on a majority of CB CD34(+) cells of preterm neonates but on only a minor popula tion of them in full-term neonates, In addition, CD33 nas dominantly expres sed on CD38(-)CD34(+) cells or CD117(low)CD34(+) cells in CB of preterm neo nates, CD33(+)CD34(+) cells of preterm cord blood had high proliferative an d reproducible potentials compared with CD33(-)CD34(+) cells, CD33(+)CD34() cells as well as CD33(-)CD34(+) cells from preterm CB highly expressed GA TA-2, in contrast to those from BM. Conclusions. These results suggest that CD33(+)CD34(+) cells, which are a m ajor population in CB CD34(+) cells of preterm neonates, do not simply repr esent relatively mature myeloid lineage hematopoietic progenitor cells as t hose in adult BM CD34(+) cells, and may contain hematopoietic stem cells or primitive progenitor cells as in fetal liver. (C) 2000 International Socie ty far Experimental Hematology. Published by Elsevier Science Inc,