2024 Immune Response Overview PDF

BIOM 611G, Medical Microbiology PCOM Georgia OVERVIEW OF THE IMMUNE...

BIOM 611G, Medical Microbiology PCOM Georgia OVERVIEW OF THE IMMUNE RESPONSE Valerie E. Cadet, PhD Assistant Dean of Health Equity Integration Professor of Microbiology and Immunology BMS1 & BMS2 Department of Biomedical Sciences November 21, 2024 EEK…OUR BODY IS UNDER ATTACK! Or The inside out From the outside in 2  3 LINES OF IMMUNE DEFENSE (NON-SPECIFIC) INNATE Physical, Biochemical and Microbial Barriers ▪ External Defenses: ▪ Skin, mucus membranes and associated hairs (ex: cilia) ▪ Fluids: sweat, tears, urine ▪ Commensal bacteria ▪ Internal Defenses: ▪ pH: Stomach acid, digestive enzymes in mouth ▪ Chemicals released from cells and damaged tissues ▪ Defensins, interferons (IFN), lysozyme, histamine 3  3 LINES OF IMMUNE DEFENSE, CON’T (NON-SPECIFIC) INNATE 2. Cellular and Protein Defenses a. Cells via non-specific recognition of microbial patterns (PAMPs) via cell receptors (PRRs) ▪ Phagocytes: white blood cells that “eat” foreign matter ▪ Natural killer cells: surveillance and killing b. Complement System: lysis of pathogen c. Inflammation: attracts white blood cells to the area and prevents spread of infection d. Fever: speeds up the activity of white blood cells and slows down viral replication 4  3 LINES OF IMMUNE DEFENSE, CON’T (Specific) Adaptive Immunity 3. Cell-mediated responses ▪ B lymphocytes (humoral response mediated by antibodies) ▪ T lymphocytes (helper and killer cells) ▪ Memory cells created 5 INNATE AND ADAPTIVE IMMUNE RESPONSES ▪ The mechanisms of innate immunity provide the initial defense against ▪ Adaptive immune responses develop later and require the activation of infections: lymphocytes: ▪ 1st and 2nd line ▪ 3rd line 6 INNATE VS ADAPTIVE RESPONSES SUMMARIZED INNATE (native): Non-specific Adaptive (Acquired): Specific Acquired over a lifetime as an adaptation to Everyone is born with this response infection Response is antigen-independent Response is antigen-dependent Lag time between exposure and maximal There is immediate maximal response response Exposure results in no immunologic Exposure results in immunologic memory memory 7  HOW OUR IMMUNE SYSTEM PROVIDES 1. DEFENSE Surveillance/Detection ▪ Watches the body for signs of damage or disease ▪ Pattern recognition receptors (innate), antigen receptors (adaptive) 2. Communication ▪ Cell-to-cell contact ▪ Chemical messages (cytokines, chemokines) 3. Elicit an effector response ▪ Attack on antigen ▪ Sometimes also on self (auto-immunity) ▪ Potential for Tissue Damage 4. Resolution of problem detected ▪ Memory (only in adaptive responses) 8 https://www.arcr.niaaa.nih.gov/arcr372/article02.htm  WHAT/ WHO ARE 9 THE MAJOR PLAYERS IN THE IMMUNE SYSTEM? Terminology to Know COMPONENTS OF THE IMMUNE SYSTEM ▪ Cells ▪ White blood cells ▪ Tissues/Organs ▪ Skin ▪ Bone Marrow ▪ Thymus ▪ Lymph nodes ▪ Spleen ▪ MALT/GALT ▪ Effector Molecules ▪ Complement system proteins ▪ Cytokines ▪ Antibodies ▪ Others 10  OUR IMMUNE SYSTEM RECOGNIZES Neoplastic or normal host cells ANTIGENS Microbial proteins and carbohydrates Streptococcus pneumoniae Viral proteins with polysaccharide antigens and carrier protein Environmental factors Antigen (Ag) Pollen Animal dander Substance that reacts with the products of a specific immune response Molecule recognized by specific receptors on T or B cells 🡪 ANTIbody GENerating Agent May be microbial or otherwise foreign to the body, neoplastic or normal host cell in origin 11 HOW OUR IMMUNE SYSTEM COMMUNICATES: CYTOKINES ▪ One of a large group of low-molecular-weight proteins secreted by various cell types ▪ Involved in cell-to-cell communication ▪ Coordinating antibody and T cell immune interactions ▪ Amplifying immune reactivity ▪ Cytokines include colony-stimulating factors (CSF), interferons (IFN), interleukins (IL), and lymphokines, which are secreted by lymphocytes ▪ Stimulate variety of immunologic functions ▪ Most have more than one function ▪ Many have overlapping functions Mosby's Medical Dictionary, 8th edition 12 HOW OUR IMMUNE SYSTEM COMMUNICATES: CHEMOKINES ▪ Any of a group of low-molecular-weight cytokines, ex: IL-8, identified on the basis of their ability to induce chemotaxis or chemokinesis in leukocytes (or in particular populations of leukocytes) in inflammation ▪ The group is divided into four subgroups on the basis of genetic, structural, and functional criteria ▪ They function as regulators of the immune system Mosby's Medical Dictionary, 8th edition 13  HOW TO IDENTIFY A CELL: CD MOLECULE Cluster of Differentiation What cell is this? How can you know? ▪ Cell surface molecules ▪ Cells can be identified in vitro and in vivo based on the types of CD molecules expressed on their membranes 14  Bacteria THE COMPLEMENT SYSTEM, AKA COMPLEMENT ▪ Series of ~ 30 serum proteins ▪ Activated sequentially following infection ▪ Leads to: ▪ Formation of opsonins ▪ Proteins which facilitate phagocytosis ▪ Acute inflammation ▪ Process whereby neutrophils leave blood stream and enter tissues in response to tissue damage (ie, infection) ▪ Cell lysis ▪ i.e., kill extracellular bacteria and other extracellular microbes 15  IMMUNE ACTIVATION CAN RESULT IN TISSUE DAMAGE Tissue damage due to: ▪ Microbe itself ▪ Cell lysis or tissue damage due to microbe replication ▪ Microbial toxins ▪ Host inflammatory responses Microbe-induce Host-induced d Tissue Tissue damage damage 16