Immunoglobulins Lecture Notes PDF

Immunoglobulins Dr. Yasir Jameel Abozaid VMD MSc PhD Clinical Epidemiology Tuesday, 24th September 2024  Immunoglobulins  Immunoglobulins, also known as antibodies, play a crucial role in our immune system.  Immunoglobulins are proteins produced by Plasma cells. ...

Immunoglobulins Dr. Yasir Jameel Abozaid VMD MSc PhD Clinical Epidemiology Tuesday, 24th September 2024  Immunoglobulins  Immunoglobulins, also known as antibodies, play a crucial role in our immune system.  Immunoglobulins are proteins produced by Plasma cells.  They are Y-shaped molecules with two heavy and two light chains.  Variability in the amino acid sequences of the variable regions allows them to recognize a vast array of antigens.  Structure of Immunoglobulins  Four polypeptide chains (2 heavy and 2 light chains)  Constant and variable regions  Linked by disulfide bond  Antigen-binding sites (hypervariable regions).  Fc and Fab  Immunoglobulin Classes  There are five main classes of immunoglobulins: IgM, IgG, IgA, IgD, and IgE.  Each class has specific functions in the immune response.  IgG subclasses  IgG 1  IgG 2  IgG 3  IgG 4  Functions of Immunoglobulins  Neutralization: Bind to pathogens or toxins, preventing them from interacting with host cells.  Opsonization: Coat pathogens, marking them for destruction by phagocytes.  Complement Activation: Trigger the complement system, leading to the lysis of pathogens.  Agglutination: Clump pathogens together, making them easier to eliminate.  Antibody-Dependent Cellular Cytotoxicity (ADCC): Bind to infected cells, marking them for destruction by immune cells like natural killer (NK) cells. Opsonization The antibodies bind to antigens on the pathogen's surface, and the Fc region of the antibody interacts with Fc receptors on phagocytes. This enhances the ability of the immune cells to engulf and destroy the pathogen. Activation Antibody-dependent cell-mediated cytotoxicity (ADCC) is a mechanism through which immune cells can kill target cells that are coated with antibodies Antibody Binding: IgG antibodies bind to specific antigens on target cells (e.g., virus- infected or tumor cells). Fc Receptor Engagement: Immune effector cells (like NK cells, macrophages, and neutrophils) express Fc receptors that bind to the Fc region of the antibodies. Cell Activation: Binding triggers the activation of effector cells, leading to the release of cytotoxic granules or pro- inflammatory cytokines. Target Cell Destruction: Perforin forms pores in the target cell membrane, allowing granzymes to enter and induce apoptosis.  Further reading Lecture notes Immunology 6th edition (Chap. 5, p. 55). Immunology 6th edition Roitt (Chap. 4, p. 65 ) Janeway’s Immunobiology 8th edition. Cellular and Molecular immunology Abbas Khan