Dr Jais Notes

• Multipotent stem cells


  Stem cells in the fetal liver and bone marrow that give rise to all lineages of blood cells, including lymphocytes
• Hematopoietic stem cells (HSCs)


  Multipotent stem cells that mature into common lymphoid progenitors that can give rise to B cells, T cells, NK cells, and innate lymphoid cells
• Commitment of common lymphoid progenitors

  1. To the B or T cell lineage

  2. Depends on transcriptional regulators that drive development toward either B cells or T cells
• Multipotent stem cells give rise to distinct B and T lineages
• Common lymphoid progenitor (CLP)

  Progenitor population that gives rise to B and T cells and also contributes to natural killer (NK) cells, innate lymphoid cells (ILCs), and some dendritic cells
• Types of B cells

  • Follicular (FO) B cells
  • Marginal zone (MZ) B cells
  • B-1 cells
• T cell lineages


  • αβ T cells
  • γδ T cells
• Transcription factors


  Involved in the maturation of T and B cells
• Notch1 and GATA3


  Commit developing lymphocytes to the T cell lineage
• EBF, E2A, and PAX5 transcription factors

  Induce the expression of genes required for B cell development
• Lymphocyte maturation


  • Involves the sequence of maturational stages shown in the illustration
  • Development of both B and T lymphocytes is similar
• Maturation of B and T lymphocytes

  1. Commitment of progenitor cells to the B lymphoid or T lymphoid lineage

  2. Proliferation of progenitors and immature committed cells at specific early stages of development

  3. Sequential and ordered rearrangement of antigen receptor genes and the expression of antigen receptor proteins

  4. Selection events that preserve cells that have produced functional antigen receptor proteins and eliminate potentially dangerous cells that strongly recognize self antigens

  5. Differentiation of B and T cells into functionally and phenotypically distinct subpopulations