Mc. Giarratana et al., Presence of primitive lymphoid progenitors with NK or B potential in ex vivo expanded bone marrow cell cultures, EXP HEMATOL, 28(1), 2000, pp. 46-54
Objective. In previous work, we showed that CD34(+) bone marrow cells can b
e successfully expanded along the myeloid pathway in stroma- and serum-free
conditions in the presence of SCF+IL-3+IL-6+Flt3-1+G-CSF+MGDF. Due to the
lack of phenotypically detectable lymphoid cells, it was necessary to addre
ss the question of the lymphoid potential of the expanded populations under
these conditions.
Materials and Methods. The present report describes a Long-term culture sys
tem that supports human B- and NK-cell differentiation from the day 14 frac
tion without further selection of the more primitive cells. In NK prolifera
tion assays, the cells were maintained over stroma cells in the presence of
IL-2 for 4-5 weeks. NK initiating cells (NK-IC) were determined by a limit
ing dilution assay, In B-cell cultures, the expanded cells were maintained
over MS5 in the presence of Flt3-1 for 4-8 weeks.
Results. NK cells rose from 0.2% +/- 0.04% at culture initiation to 71% +/-
6% at week 5. These cells displayed cytolytic activity, NK-IC evaluation s
howed a mean 18-fold expansion in the day 14 expanded fraction as compared
to the initial day 0 fraction, Similarly, CD19(+) cells rose from 0.1% at c
ulture initiation to 30% +/- 1% at week 6. Cells produced under these B-LTC
conditions were CD34(-)CD19(+)CD10(+). We also demonstrated that the CD34(
+)/Lin(-) sorted cells from the day 14 fraction gave rise to NK and B cells
.
Conclusion. This culture system permits the revelation of a population that
, although poorly represented in terms of phenotypically detectable cells,
nevertheless retains high levels of lymphoid NK and B potential after 14 da
ys expansion. Such data suggest the persistence, or expansion, of lymphoid
progenitors and, hence, the multipotentiality of the expanded progenitor/st
em cells, (C) 2000 International Society for Experimental Hematology. Publi
shed by Elsevier Science Inc.