Lymphocytes Development and Maturation PDF

In the Name of God Lymphocytes Development and Maturation Hossein Asgarian-Omran Ph.D., Prof. of Immunology Dep. of Immunology, School of Medicine Mazandaran University of Medical Sciences...

In the Name of God Lymphocytes Development and Maturation Hossein Asgarian-Omran Ph.D., Prof. of Immunology Dep. of Immunology, School of Medicine Mazandaran University of Medical Sciences Sari, Iran [email protected] Outlines  Different stages of B and T lymphocyte maturation  Checkpoints in lymphocyte development  Rearrangement or recombination of immunoglobulin and T lymphocyte receptor genes  Maturity and development of B lymphocytes and different selections  Maturity and development of T lymphocytes and different selections Maturation stages of B and T lymphocytes IL-7 B Cell Receptor (BCR) T Cell Receptor (TCR) Checkpoints in lymphocyte development Gene Rearrangement or Gene Recombination of BCR and TCR genes  Variable domain Constant domain Different immunoglobulin domains ? ? Different TCR domains ? ? Variable domain is created from different gene fragments Genes encoding the Genes encoding the variable domain constant domain V (D) J 3 gene fragments are A single gene fragment plays involved in the construction a role in the construction of of the variable domain the constant domain  Rag-2 ‫ و‬Rag-1 Enzymes Recombination Activating Genes They are enzymes that recognize specific sequences and cause double-stranded DNA cleavage.  Sequence of events during VDJ rearrangement 1. Synapsis 2. cleavage 3. coding end processing 4. joining Addition of N and P nucleotides – Junctional Diversity C segments  Different factors causing diversity in immunoglobulin and TCR chains Combinational and Junctional Diversity 1. Different types of V, D and J genes on the genome 2. Different combinations of different types of V, D and J genes 3. Addition of P and N nucleotides 4. Combination of types of light and heavy chains or α and β  Origin and production of B cells B lymphocytes are produced throughout life by hematopoietic progenitor cells (stem cells) in the bone marrow. In the embryonic period: first in the yolk sac and para-aortic mesenchyme Then in the liver Maturation stages of B lymphocytes Different subsets of B lymphocyte Origin and Production of T Cells T lymphocytes are produced throughout life by hematopoietic stem cells (stem cells) in the bone marrow and undergo their development in the thymus. In the embryonic period: liver and spleen Maturation stages of T lymphocytes Double negative Maturation of T lymphocytes in the thymus Positive and negative selection in T lymphocytes development