Long-lived polyclonal B-cell lines derived from midgestation mouse embryo lymphohematopoietic progenitors reconstitute adult immunodeficient mice

Lymphohematopoietic progenitors derived from midgestation mouse embryos wer e established in long-term cultures with stromal cell monolayers and interl eukin 7 (IL-7), giving rise to B-lineage cell lines. The initial emergence and in vitro establishment of these early embryo cell lines were highly sen sitive to IL-7-mediated signals, in comparison to cell lines similarly obta ined using precursors from late fetal liver (> 13 days postcoitum) and adul t bone marrow. The early embryo-derived progenitors spontaneously different iated in vitro to CD19(+)IgM(+) immature 8 cells in the presence of optimal concentrations of IL-7, in contrast to those progenitors obtained from lat e gestation and adult mice, whose differentiation only occurred in the abse nce of IL-7. The newly in vitro-generated B cells of the early embryo cell lines repopulated adult immunodeficient severe combined immunodeficient mic e on their adoptive transfer in vivo and generated specific humoral immune responses after immunization.