Antigen Presenting Cells Bcells Macrophage Dendritic Cell Immunology

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This video is about Antigen presenting cells: • Content: • 0:00 Introduction • 0:10 Function of Antigen-Presenting Cells (APCs) • 3:01 Types of APC • 4:29 B-Lymphocyte Development • 9:33 B-Lymphocyte Function • 15:43 Macrophage/Dendritic Cell Development • 17:11 Macrophage Function • 22:40 Dendritic Cell Function • ------------------------------- • 🫀 Join: / @taimtalksmed • 📷 Follow my IG: / taimtalksmed • 💝 Donation link: https://www.buymeacoffee.com/taimtalk... • ------------------------------- • -------------------------------------------------------------------------------- • All information in my immunology videos are from: • Book: Immunology, Eighth Edition by David Male, Jonathan Brostoff, David Roth and Ivan Roitt • Additional research in PubMed • University lecture materials • -------------------------------------------------------------------------------- • What are antigen presenting cells (APC)? • Phagocyte microorganisms and present them on MHC I or MHC II • They express B7 (Co-stimulator for T-cells) • Presents MHC II to Naive T-Helper Cells (CD4+ cells). • 3 activation signals are required to activate naive T-helper cells: • 1st activation signal: MHCII-TCR(CD4 and CD3) • 2nd activation signal: B7 - CD28 • 3rd activation signal: Interleukins • MHC I activate T-cytotoxic cells (CD8+ cells) • Professional Antigen Presenting Cells: • B-Lymphocytes • Macrophages • Dendritic Cells • Inactive/unprofessional antigen presenting cells: • Langerhans Cells • B-Lymphocytes: • Normal: Antibodies produces against specific antigens • B-cells produce surface antibodies randomly during development. Apoptosis happen if they are not exposed to antigens whithin a certain amount of time (Anergy) • B-Lymphocyte Developement: • In Spongy Bone: • Start as Pluripotent Hematopoietic Stem Cell • Pro B-Cell • Pre B-cell (Recombination of Heavy chain for IgM gene VDJ gene) • Immature B-cell (Recombination of light chain gene VJ gene) IgM development complete • Mature B-cell have IgM and IgD antibodies on surface • Then they're controlled whether they self react or not. If non self reactive - Travel to secondary lymphoid organs (Lymph node, spleen, payers patches) • B-Lymphocyte steps of activation: • B cell receptor (BCR) consist of IgD/IgM and signal chains (Iga and Igb) • B-cells are located in outer cortex of lymph node. • 1. BCR react with antigen • 2. BCR mediated endocytosis • 3. Present it on MHC II to Th2 or Th0 • 4. Th2 binds to activated B-cell through (CD40L-CD40) and (TCR-MHCII) • 5. Cytokines released to help B-cell differentiate (IL-4, IL-5, IL-10, IL-6, IL-2 and IFN-g) • 6. B-cell become Memory B cell and Plasma Cells (specific type of plasma cell) • When T-cells help B-cells differentiate (T-cell dependent B-cell differentiation) - They become IgA, IgE or IgG • T-independent B-cell differentiation: Quick process which produce IgM when a polysaccharide binds to BCR and activate B-cells. No memory B-cells are produces. • Macrophages Developement: • 1. Pluripotent hematopoietic Stem Cell • 2. Mono Stem Cell • 3. Pro-monoblast • 4. Monoblast • 5. Pro-monocyte • 6. Monocyte in blood • 7. Monocyte become Free macrophage in tissue, fixed macrophages or dendrittic cell • Functions of Macrophage: • MHC 1/2 • Fc IgG (direct opsonization) • Fc IgE • C3b receptor for C3b of complement • CD14 for Lipopolysaccharide (LPS) • B7 • Active Macrophage can release: • Interleukin 12 (IL12) - differentiate Th0 to Th1 and activate Natural Killer cells • Interleukin 8 (IL8) - Chemotaxis • Interleukin 1, Interleukin 6 and Tumor necrotic factor alpha work as endogenic pyrogens • IL1, IL6 and TNFa goes to hypothalamus • Hypothalamus release Prostaglandins E2 • IL6 can travel to liver and cause release of Acute phase proteins • Dendritic Cells: • Come from monocytes in the blood • Can migrate easily • Surface of Dendritic cells: • MHC1 and MHC 2 • B7 • Adhesion molecules that promote T-ly attachment. • Langerhans cells: • Also called immature dendritic cell • Once they phagocyte, they travel to lymph node and start to express B7

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