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Semester 3: M.Sc. Biotechnology Syllabus 2023-2024
History and overview of the immune system. Types of immunity - innate, acquired, passive and active, self vs non-self-discrimination. Physiology of immune response HI and CMI specificity and memory. Cells and organs of the immune system .Lymphoid tissue, origin and development. Hematopoiesis and differentiation of lymphocytes
History and Overview of the Immune System
Ancient Understanding of Immunity
Historical observations of disease and recovery led to early concepts of immunity, with documentation from ancient civilizations like Egypt and China about protecting against infectious diseases.
Development in the 19th Century
With the work of scientists like Louis Pasteur and Robert Koch, the germ theory of disease emerged, leading to advancements in vaccination and understanding of microorganisms.
Modern Immunology
The establishment of immunology as a scientific discipline in the 20th century, characterized by the discovery of antibodies, antigens, and elucidation of immune cell functions.
Innate Immunity
First line of defense against pathogens, non-specific, involving physical barriers and immune cells such as macrophages and natural killer cells.
Acquired Immunity
Specific immunity developed after exposure to pathogens, involving lymphocytes and the generation of memory cells.
Active Immunity
Immunity gained through exposure to antigens leading to long-term protection; can be natural (infection) or artificial (vaccination).
Passive Immunity
Short-term immunity acquired by receiving antibodies from another organism, either naturally (maternal antibodies) or artificially (injections).
The ability of the immune system to distinguish between the body's own cells (self) and foreign invaders (non-self), crucial for preventing autoimmune diseases.
Involves B cells and the production of antibodies that circulate in blood and lymph, targeting specific antigens.
Involves T cells which recognize and destroy infected cells or coordinate other immune responses.
Immune responses are highly specific to particular pathogens, and memory cells enhance the speed and quality of responses upon re-exposure.
Includes lymphocytes (B cells, T cells), antigen-presenting cells (dendritic cells, macrophages), and organs like the thymus, spleen, and lymph nodes.
Lymphoid tissues are crucial for immune function, developing from precursor cells in the bone marrow and migrating to various sites for maturation.
The process by which stem cells in the bone marrow give rise to different blood cells, including lymphocytes, essential for the immune response.
Lymphocyte-sub-populations of mouse and man. APC cells, lymphokines, Phagocytic cells, macrophage, dendritic cells, K and NK Cells. Nature and biology of antigens, epitopes, haptens, adjuvents. Immunoglobulins- structure, distribution and function. Immunoglobulin super family Isotypic, Allotypic and Idiotypic variants, generation of antibody diversity
Lymphocyte-sub-populations of mouse and man
Lymphocyte Subpopulations in Mice
Mice possess distinct lymphocyte subpopulations including B cells, T cells, and NK cells. Each subpopulation has specific functions such as antibody production and cytotoxic activity. Their development and differentiation are influenced by cytokines and interactions with antigen-presenting cells (APCs).
Lymphocyte Subpopulations in Humans
Human lymphocyte populations are similar to those in mice but exhibit unique surface markers and functional characteristics. The main types include CD4+ helper T cells, CD8+ cytotoxic T cells, B cells, and various NK cells. Understanding these differences is vital for immunological research and therapeutic approaches.
Antigen-Presenting Cells (APCs)
APCs such as dendritic cells, macrophages, and B cells play a crucial role in displaying antigens to T cells, facilitating an adaptive immune response. Dendritic cells are particularly efficient in antigen capture and presentation, leading to T cell activation.
Lymphokines
Lymphokines are cytokines produced by lymphocytes that have a wide range of immune functions, including the regulation of inflammation, hematopoiesis, and activation of other immune cells. They play essential roles in intercellular communication during immune responses.
Phagocytic Cells
Phagocytic cells, including macrophages and neutrophils, are responsible for engulfing and digesting pathogens and debris. They play a key role in both innate immunity and the subsequent activation of adaptive immunity.
Macrophages
Macrophages are versatile immune cells derived from monocytes. They can be classified into M1 and M2 subtypes, where M1 promotes inflammatory responses and M2 is involved in tissue repair and resolution of inflammation.
Dendritic Cells
Dendritic cells act as professional APCs, bridging innate and adaptive immunity. They capture, process, and present antigens to T cells, inducing primary immune responses.
K Cells and NK Cells
K cells, a type of cytotoxic lymphocyte, and NK cells are critical for the innate immune system. NK cells recognize and kill infected or transformed cells without prior sensitization and play a significant role in immune surveillance.
Nature and Biology of Antigens
Antigens are molecules that can provoke an immune response. They can be proteins, polysaccharides, or nucleic acids and can be classified into immunogenic and non-immunogenic categories.
Epitopes and Haptens
Epitopes are specific parts of an antigen that are recognized by antibodies or receptors on T cells. Haptens are small molecules that become immunogenic when attached to a larger carrier protein.
Adjuvants
Adjuvants are substances that enhance the immune response to an antigen. They are commonly used in vaccines to improve their efficacy.
Immunoglobulins
Immunoglobulins (Ig) are antibodies produced by B cells. They come in five classes (IgG, IgA, IgM, IgE, IgD) with varied distribution and function in the immune system, including pathogen neutralization and opsonization.
Immunoglobulin Superfamily
The immunoglobulin superfamily comprises a large group of proteins involved in various immune responses. They are defined by their structural features and include receptors and adhesion molecules.
Isotypic, Allotypic, and Idiotypic Variants
Isotypic variants refer to different classes of antibodies. Allotypic variants are differences between individuals within the same species, while idiotypic variants are unique to the antibodies produced by an individual.
Generation of Antibody Diversity
Antibody diversity arises through mechanisms such as V(D)J recombination, somatic hypermutation, and class switch recombination, allowing the immune system to recognize a vast array of antigens.
Monoclonal antibody production and its applications. Types of vaccine and vaccination schedule. Role of MHC antigens in immune responses, Structure and function of class I and class II MHC molecules. MHC antigens in transplantation and HLA tissue typing. Transplantation immunology- immunological basis of graft rejection, clinical transplantation and Immunosuppressive therapy. Tumour Immunology - Tumour antigen, Immune response to tumours
Monoclonal Antibody Production
Monoclonal antibodies are identical antibodies produced from a single clone of B cells. The production process involves immunizing an animal, typically a mouse, with an antigen to stimulate an immune response. B cells that produce the desired antibody are fused with myeloma cells to create hybridomas. These hybridomas are then screened for antibody production, cloned, and expanded to produce large quantities of monoclonal antibodies. Applications include diagnostics, therapeutics, and research tools.
Types of Vaccine and Vaccination Schedule
Vaccines can be classified into live attenuated, inactivated, subunit, and mRNA vaccines. Live attenuated vaccines use weakened forms of the pathogen; inactivated vaccines use killed pathogens; subunit vaccines use protein or carbohydrate antigens; mRNA vaccines utilize genetic material to prompt an immune response. Vaccination schedules vary by age, health status, and type of vaccine, typically including primary series, boosters, and special recommendations for high-risk groups.
Role of MHC Antigens in Immune Responses
Major Histocompatibility Complex (MHC) antigens play a critical role in the immune system by presenting peptide antigens to T cells. This activation is essential for adaptive immunity. MHC class I molecules present endogenous antigens to CD8+ cytotoxic T cells, while MHC class II molecules present exogenous antigens to CD4+ helper T cells.
Structure and Function of Class I and Class II MHC Molecules
Class I MHC molecules are composed of a heavy chain and a beta-2 microglobulin, presenting peptides to CD8+ T cells. They are expressed on nearly all nucleated cells. Class II MHC molecules consist of two chains, alpha and beta, and are primarily found on antigen-presenting cells, presenting to CD4+ T cells. Both classes are crucial for T cell development and activation.
MHC Antigens in Transplantation and HLA Tissue Typing
In transplantation, MHC antigens are crucial for graft acceptance or rejection. Human Leukocyte Antigen (HLA) typing is performed to match donor and recipient tissues to minimize the risk of rejection. Mismatched HLA can lead to acute or chronic rejection of the transplant.
Transplantation Immunology
Transplantation immunology studies the immune response to transplanted tissues. Graft rejection can be either hyperacute, acute, or chronic. Immunosuppressive therapy is employed to prevent rejection, using agents that inhibit immune activation, such as corticosteroids, calcineurin inhibitors, and mTOR inhibitors.
Tumor Immunology
Tumor immunology explores the immune system's response to cancer cells. Tumor antigens can be classified into tumor-specific antigens and tumor-associated antigens. The immune response to tumors involves various immune cells, including T cells and natural killer cells, and understanding this response is critical for developing immunotherapies.
Effector mechanisms in immunity - macrophage activation, cell mediated cytotoxicity, cytotoxicity assay. Hypersensitivity reactions and types. The complement system, mode of activation, classical and alternate pathway, biological functions of C proteins
Effector mechanisms in immunity
Macrophage Activation
Macrophages are a key component of the innate immune system. Activation can occur through various signals including cytokines, pathogen-associated molecular patterns (PAMPs), and danger-associated molecular patterns (DAMPs). Once activated, macrophages undergo a phenotypic change, enhancing their phagocytic ability, increasing the production of reactive oxygen species (ROS), and releasing pro-inflammatory cytokines.
Cell Mediated Cytotoxicity
This form of immunity is primarily mediated by T cells, particularly cytotoxic T lymphocytes (CTLs). Upon recognizing antigens presented by Major Histocompatibility Complex (MHC) molecules on infected or tumor cells, CTLs release perforin and granzymes that induce apoptosis in target cells. Natural Killer (NK) cells also participate in this process by recognizing stress-induced ligands on target cells.
Cytotoxicity Assay
Cytotoxicity assays are used to measure the effectiveness of immune responses in destroying infected or cancerous cells. Common methods include the lactate dehydrogenase (LDH) assay, MTT assay, and flow cytometry-based assays. These assays help evaluate the function of immune cells and the impact of therapies.
Hypersensitivity Reactions
Hypersensitivity reactions are exaggerated or inappropriate immune responses that can lead to tissue damage. They are classified into four types: Type I (IgE-mediated reactions such as allergies), Type II (antibody-mediated cytotoxicity), Type III (immune complex-mediated), and Type IV (delayed-type reactions mediated by T cells). Each type has distinct mechanisms and clinical manifestations.
The Complement System
The complement system is a group of serum proteins that play a crucial role in innate and adaptive immunity. It can be activated via three pathways: the classical pathway, which is initiated by antibody-antigen complexes; the alternative pathway, which is activated by microbial surfaces; and the lectin pathway, triggered by mannose-binding lectin binding to carbohydrates on pathogens. Biological functions include opsonization of pathogens, recruitment of inflammatory cells, and lysis of pathogens via the membrane attack complex.
Biological Functions of C Proteins
Complement proteins (C proteins) serve various functions including opsonization which enhances phagocytosis, chemotaxis that recruits immune cells to sites of infection, and the formation of the membrane attack complex that directly lyse target cells. Their regulated activation is vital to prevent tissue damage.
Immunotechniques- Principle and Applications Immunodiffusion, Immuno fluorescence, In-situ localization technique - FISH and GISH. RIA and ELISA, FACS, Western blot, ELISPOT assay. Agglutination tests. VDRL test. Purification of antibodies, Quantitation of immunoglobulin by RID, EID and nephelometry, CMI techniques and Immunotherapy
Immunotechniques
Immunodiffusion
This technique involves the diffusion of antigen and antibody in a gel, leading to the formation of a precipitin line. It is primarily used for identifying and quantifying specific antigens or antibodies in a sample.
Immunofluorescence
This method utilizes fluorescent-labeled antibodies to detect specific proteins in cells or tissue sections. It allows visualization under a fluorescence microscope and is valuable in diagnosing infections and autoimmune diseases.
RIA and ELISA
Radioimmunoassay (RIA) utilizes radioactively labeled antigens or antibodies for quantification, while Enzyme-Linked Immunosorbent Assay (ELISA) uses enzyme-linked antibodies for detecting and quantifying proteins in a sample. Both are widely used in clinical diagnostics.
FISH
Fluorescence In Situ Hybridization is a cytogenetic technique that uses fluorescent probes to bind to specific DNA sequences on chromosomes. It is used for genetic mapping and detecting chromosomal abnormalities.
GISH
Genomic In Situ Hybridization is similar to FISH but involves the use of total genomic DNA as probes. It is mainly used for the study of plant genomes and chromosomal rearrangements.
FACS
Fluorescence-Activated Cell Sorting is a specialized type of flow cytometry that sorts a heterogeneous mixture of cells into different populations based on their fluorescent characteristics.
Western Blot
This technique is used for detecting specific proteins in a sample. It involves electrophoresis for separation, transfer to a membrane, and probing with specific antibodies.
ELISPOT Assay
Enzyme-Linked ImmunoSpot Assay is used to measure the frequency of cells secreting specific proteins. It is widely used in immunology and vaccine development.
Agglutination Tests
These tests are based on the clumping of particles in the presence of specific antibodies. They are commonly used for blood typing and identifying infections.
VDRL Test
The Venereal Disease Research Laboratory test is a non-treponemal test for syphilis that detects reagin antibodies in the plasma.
Purification of Antibodies
Various methods exist for purifying antibodies, including affinity chromatography, where antibodies are separated based on their specific binding to antigens.
CMI Techniques
Cell-Mediated Immunity techniques encompass various assays to assess T-cell responses, including skin tests and proliferation assays.
RID
Radial Immunodiffusion is a technique used to measure the concentration of antibodies or antigens in a sample based on their diffusion rates.
EID
Electrophoretic Immunodiffusion involves the application of an electric field to facilitate the movement of charged molecules within a gel matrix.
Nephelometry
This method measures the scattered light from immune complexes formed in solution, allowing for the quantification of specific proteins.
Immunotherapy
This approach harnesses the body's immune system to treat diseases, particularly cancers and autoimmune conditions, using monoclonal antibodies and other immune-modulating therapies.
