Description
This tertiary-level lecture by Dr S. M. Munsaka focuses specifically on innate immunity as part of the broader immune system. Delivered under the course code BMS 3325 at the University of Zambia's Department of Biomedical Sciences, the material is designed for students pursuing a degree, diploma, or certificate in biomedical sciences or related health programmes. It details the body's first and second lines of defense, covering anatomical, chemical, and physiological barriers as well as the cellular components of innate immunity, including phagocytes (monocytes, macrophages, neutrophils, dendritic cells), natural killer cells, and granulocytes (eosinophils, basophils, mast cells). The notes explain the function and mechanisms of key innate elements such as antimicrobial peptides like defensins, Type I Interferons, the complement system, and the inflammatory response. It introduces the concept of pathogen-associated molecular patterns (PAMPs) and their recognition by pattern recognition receptors, including Toll-like receptors (TLRs). The lecture also connects innate immunity to infectious disease, discussing host-microbe interactions, the benefits of normal flora, and provides a historical overview of emerging pathogens. This resource serves as an essential foundation for understanding non-specific host defenses, crucial for students preparing for university examinations in immunology and microbiology. Access these notes to build a solid understanding of innate immune mechanisms for academic success.
What's inside
Introduction to the Immune System (Innate Immunity) BMS 3325 S. M. Munsaka, BSc., MSc., PhD Department of Biomedical Sciences School of Health Sciences The University of Zambia 21st May 2020 Lecture Structure/Objectives Cells and tissues of the immune system Lymphocytes, antigen presenting cells and granulocytes Primary and secondary lymphoid organs Bone marrow, thymus, spleen, lymph nodes, mucosal associated lymphoid tissues and cutaneous associated lymphoid tissues Basic development morphology and function of the immune system and immune cells Introduction to infectious disease Structure of the Immune System First line: Anatomical /Mechanical barriers (Skin and mucous membranes) Chemical barriers (acid and antibacterial peptides) Complement proteins, lysozyme and defensins Physiological barriers (temperature, pH) Second line: innate immune cells Phagocytes (monocytes/macrophages, neutrophils and dendritic cells) Natural killer cells (NKCs) Inflammatory cells (mast cells, basophils, eosinophils) Third line: adaptive immune cells Lymphocytes (T cells and B cells) Humoral immunity: Immunoglobulins (antibodies) Cell-medicated immunity: T cells Effector and memory responses •Humoral immunity: Antibodies in circulation eliminate infectious agent •Mechanisms •Neutralization/blocking •Antibody dependent-cell mediated cytotoxicity (ADCC) •Opsonization •Complement fixation •Cell-mediated immunity: T cells activate macrophage to kill phagocytosed microbe or kill infected cells Two Types of Acquired Immune Responses Development of Cells of the immune system Cells of the immune system Lymphocytes B and T cells (Th/CD4 and Tc/CD8 cells) Natural killer cells (NK cells) Antigen presenting cells B cells, monocytes/macrophages, dendritic cells Cells that produce inflammatory mediators (granulocytes) Neutrophils, basophils, eosinophils, mast cells Important in helminth and protozoan infections Involved in allergy Effector function of immunoglobulins NK cells Have Inhibitory and Activating Receptors Inhibitory receptors Recognize class I MHC (major histocompatibility) molecules) Transmit an inhibitory signal that blocks activation Activating receptors Works only when MHC I expression is lost Virus infected and tumor cells often lose class I MHC expression Monocytes/macrophages Monocytes originate from the bone marrow and mature in the blood (blood monocytes) Circulate in blood a few days and migrate into tissues where they differentiate into tissue macrophages Alveolar macrophages in lungs Histiocytes in connective tissue Kupffer cells in the liver Mesangial cells in the kidneys Microglia in the brain Osteoclasts in the bones Function as antigen presenting cells and phagocytes Express MHC-II Activated by IFN-γ
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