Immunology

• Haematopoiesis is the process of blood cell formation
• Lymphocytes are a type of White Blood Cell (WBC) with diverse functions
• B cells are produced in the bone marrow, while T cell precursors are produced in the bone marrow and mature in the thymus
• B Cell Receptor (BCR) & T Cell Receptor (TCR) have:

  • Antigen specificity
  • Integral membrane proteins
  • Thousands of identical copies exposed at the cell surface
  • Made before antigen encounter
  • Encoded by genes assembled by DNA recombination
  • Unique binding site for antigen epitope
• Differences between BCR & TCR include:

  • Structure
  • Encoding genes
  • Type of epitope they bind to
• Lymphocyte development involves the differentiation of lymphocyte progenitors in the thymus and bone marrow into mature lymphocytes
• Maturation of B & T lymphocytes is initiated by signals from cell surface receptors, promoting proliferation of progenitors and rearrangement of antigen receptor genes
• B Cell Development:

  • Early stages dependent on Bone Marrow Stromal cells
  • Proceeds through stages defined by rearrangement & expression of Ig genes
• T cell precursors travel from the bone marrow to develop in the thymus, then mature T cells move to secondary lymphoid tissues
• Stages of T Cell maturation include Positive Selection and Negative Selection
• Haematopoiesis:

  • Process of blood cell formation
  • Includes the development of B and T cells
• Lymphocytes are a type of White Blood Cell (WBC) with diverse functions, including B Lymphocytes (B cells) and T Lymphocytes (T cells)

  • B cells are produced and mature in the bone marrow
  • T cells are produced in the bone marrow and mature in the thymus
• B Cell Receptor (BCR) & T Cell Receptor (TCR) have antigen specificity

  • Similarities: integral membrane proteins, thousands of identical copies exposed at the cell surface, made before antigen encounter, encoded by genes assembled by DNA recombination, presence of unique binding site for antigen epitope
  • Differences: structure, encoding genes, type of epitope they bind to
• Lymphocyte development (maturation) is the process by which lymphocyte progenitors in the thymus and bone marrow differentiate into mature lymphocytes that populate peripheral lymphoid tissues

  • Maturation is initiated by signals from cell surface receptors
  • Roles: promote progenitor proliferation and initiate rearrangement of antigen receptor genes
• Commitment to the B and T Cell Lineages and Proliferation of Progenitors
• Stages of Lymphocyte maturation
• Checkpoints in lymphocyte maturation
• B Cell Development:

  • Early B cell development depends on bone marrow stromal cells
  • Proceeds through stages defined by the rearrangement and expression of the Ig genes
• The Pathway of T cell Development:

  • T cell precursors travel from the bone marrow to develop in the thymus
  • Mature T cells leave the thymus and travel to secondary lymphoid tissues
• Stages of T Cell maturation:

  • Positive Selection
  • Negative Selection
• T Cell Functions