Increased ID2 Levels in Adult Precursor B Cells as Compared with Children Is Associated with Impaired Ig Locus Contraction and Decreased Bone Marrow Output

Abstract

Precursor B cell production from bone marrow in mice and humans declines with age. Because the mechanisms behind are still unknown, we studied five precursor B cell subsets (ProB, PreBI, PreBII large, PreBII small, immature B) and their differentiation-stage characteristic gene expression profiles in healthy individual toddlers and middle-aged adults. Notably, the composition of the precursor B cell compartment did not change with age. The expression levels of several transcripts encoding V(D)J recombination factors were decreased in adults as compared with children: RAG1 expression was significantly reduced in ProB cells, and DNA-PKcs, Ku80, and XRCC4 were decreased in PreBI cells. In contrast, TdT was 3-fold upregulated in immature B cells of adults. Still, N-nucleotides, P-nucleotides, and deletions were similar for IGH and IGK junctions between children and adults. PreBII large cells in adults, but not in children, showed highly upregulated expression of the differentiation inhibitor, inhibitor of DNA binding 2 (ID2), in absence of changes in expression of the ID2-binding partner E2A. Further, we identified impaired Ig locus contraction in adult precursor B cells as a likely mechanism by which ID2-mediated blocking of E2A function results in reduced bone marrow B cell output in adults. The reduced B cell production was not compensated by increased proliferation in adult immature B cells, despite increased Ki67 expression. These findings demonstrate distinct regulatory mechanisms in B cell differentiation between adults and children with a central role for transcriptional regulation of ID2.

Chronic lymphocytic leukaemia: could immunological tolerance mechanisms be the origin of lymphoid neoplasms?

“…ID‐1 is expressed only in pro‐B cells. However, pre‐B cells in adults, showed highly up‐regulated expression of ID‐2, in the absence of changes in expression of E2A in bone marrow. Over‐expression of ID‐2 in follicular lymphoma cells may regulate proliferation or contribute to the maturation arrest in these tumour cells .…”

Nuclear positioning rather than contraction controls ordered rearrangements of immunoglobulin loci

“…BAC clones CT7–526A21, RP23–24I12, CT7–34H6 for detecting regions in the murine Igh locus ( 27 ), and RP23–234A12, RP24–475M8, RP23–435I4 recognizing regions within murine Igκ locus (all from BACPAC Resources) were used as FISH probes. Probe labeling and DNA FISH were performed as described previously ( 27 , 40 – 41 ). Images were acquired on a Leica SP5 confocal microscope (Leica Microsystems), followed by deconvolution and analysis with Huygens Professional software (Scientific Volume Imaging) ( 40 , 41 ).…”

The Human Thymus Is Enriched for Autoreactive B Cells

“…B cell subsets were purified from homogenized pediatric thymuses, fetal limb BM suspensions, and pediatric BM aspirates as described previously (11,(19)(20)(21)(22) (17,23,24), Ig cloning, and Ab expression procedures were performed as described previously (15,17,23,24). The usage of V, D, and J genes as well as the junctional regions were analyzed using the international ImMunoGeneTics information system (http://www.imgt.org/) (25).…”