ORIGINAL ARTICLE: B-cell reconstitution by transplantation of B220 super(+) CD117 super(+) B-lymphoid progenitors into irradiated mice

Bone marrow cells of 4-week-old CBA-J mice were searched for progenitors that can reconstitute CBA-type B lineage (B220 super(+)) cells after transplantation into irradiated (BALB-c x CBA-J) F sub(1) mice. In recipients of B lineage-committed B220 super(+) CD117 super(+) cells, which were CD19 super(+) CD127 super(+) CD25 super(-) IgM super(-), numbers of CBA-type B220 super(+) cells had increased greatly by day 8 after transplantation. This increase stopped by day 10 but cell numbers remained at this level for at least 8 weeks. B-cell production in the bone marrow of B220 super(+) CD117 super(+) cell recipients occurred even 8 weeks after transplantation. Probably, the transplanted B-lymphoid progenitors are capable of self-renewing up to 8 weeks after transplantation. B lineage- uncommitted CD117 super(high) CD71 super(-) cells, which were B220 super(-) and included haematopoietic stem cells, could also reconstitute B lineage bone marrow cells after transplantation. Sequential development of CD117 super(+), CD25 super(+) and IgM super(+) cells in CBA-type B220 super(+) bone marrow cells occurred 2-4 days faster in recipients of B220 super(+) CD117 super(+) progenitors than in recipients of CD117 super(high) CD71 super(-) progenitors, suggesting that the development of the former progenitors from the latter may take 2-4 days.