A developmental switch between fetal and adult B lymphopoiesis.
Fluorescence-activated cell sorting (FACS)-purified pro-B cells from fetal liver and adult bone marrow generate B cells with distinct phenotypes: fetal cells generate few IgD(high) B cells and half express CD5, whereas adult cells generate mostly IgD(high) cells and few express CD5. These results led us to propose a model of a developmental switch in B lymphopoiesis, similar to the well-known switch in fetal to adult erythropoiesis. More recent global analysis of mRNA and microRNA expression comparing these two types of pro-B cells revealed differential expression of Lin28b and microRNAs from the Let-7 family, indicating that this regulatory axis plays a role in the switch. Further analysis has provided data supporting this model, implicating Arid3a as a key transcription factor in mediating fetal-type B cell development. Function of this regulatory axis in human B lineage precursors may also explain the predominance of CD5(+) B cells in cord blood. We suggest that Lin28b-promoted B cell development generates many cells expressing CD5 as a consequence of positively selected self-reactivity. While such cells serve a useful role in clearance of senescent cells and in certain immune responses, they also carry the risk of progression to leukemia/lymphoma later in life.
Fox Chase Cancer Center, Philadelphia, Pennsylvania.
Yue-Sheng
YS
Li
Fox Chase Cancer Center, Philadelphia, Pennsylvania.
Yan
Y
Zhou
Fox Chase Cancer Center, Philadelphia, Pennsylvania.
Lingjuan
L
Tang
Fox Chase Cancer Center, Philadelphia, Pennsylvania.
Susan A
SA
Shinton
Fox Chase Cancer Center, Philadelphia, Pennsylvania.
Kyoko
K
Hayakawa
Fox Chase Cancer Center, Philadelphia, Pennsylvania.
Richard R
RR
Hardy
D000328:Adult; D016175:B-Lymphocyte Subsets / Q000502:physiology*; D001402:B-Lymphocytes / Q000502:physiology; D005333:Fetus / Q000166:cytology* / Q000502:physiology*; D006801:Humans; D038041:Lymphopoiesis / Q000502:physiology*
B1a B cell; adult development; cord blood; fetal development; hematopoietic stem cells