Title

xid mice reveal the interplay of homeostasis and Bruton's tyrosine kinase-mediated selection at multiple stages of B cell development

GSBS Program

Biochemistry & Molecular Pharmacology

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Molecular Genetics and Microbiology; Department of Physiology

Date

11-22-2001

Document Type

Article

Medical Subject Headings

Animals; B-Lymphocyte Subsets; Bone Marrow Cells; Cell Cycle; Cell Differentiation; Cell Lineage; Female; Flow Cytometry; Gene Expression Regulation; Homeostasis; Humans; Immunologic Deficiency; Syndromes; Lymphocyte Count; Male; Mice; Mice, Inbred CBA; Mice, Transgenic; Protein-Tyrosine Kinases; Proto-Oncogene Proteins c-bcl-2; Spleen; Transgenes; X Chromosome

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

Human X-linked agammaglobulinemia (XLA) and murine X-linked immune defect (XID) are both immunodeficiencies mediated by mutations in Bruton's tyrosine kinase (Btk), yet the developmental stage(s) affected remain controversial. To further refine the placement of the XID defect(s), we used bromodeoxyuridine labeling to determine turnover, production and transition rates of developing B cell subsets in normal, xid and xid mice expressing a human Bcl-2 transgene (xid/bcl-2). We find the xid mutation manifest at two stages of B cell development. The first is early, reducing pre-B cell production by restricting pro-B to pre-B cell transit. Surprisingly, this impairment is offset by increased survival of cells progressing from the pre- to immature B cell pool, suggesting that Btk-independent homeostatic mechanisms act to maintain this compartment. The second point of action is late, substantially reducing mature B cell production. Together, these findings reconcile apparent discrepancies in the developmental stage affected by the murine versus human lesions and suggest previously unappreciated homeostatic processes that act at the pre-B to immature B cell transition. Finally, Btk likely functions differently at these two checkpoints, since ectopic Bcl-2 expression fails to directly complement the early xid lesion, yet reverses the defect impeding final B cell maturation.

Rights and Permissions

Citation: Int Immunol. 2001 Dec;13(12):1501-14.

Related Resources

Link to article in PubMed