Introduction to Immunology - Chapter 1 Overview

Introduction to Immunology

• The module covers immunology, a crucial subject
• The content is from Dr Cristina Keightley
• Key reference: Chapter 1 – Introduction to the immune system in Abbas et al. 7th Ed.

Module Overview

• The module is divided into modules
• Module 1 provides an overview of innate immunity, cells, and barrier immunity
• Module 2 covers pathogen recognition and cells involved in the innate response
• Module 3 focuses on antigen presentation and the immune synapse
• Module 4 discusses immunopharmacology and the innate immune system, including glucocorticoids
• Module 5 explains cell development, clonal diversity, and tolerance

What is Immunology and Why is it Important?

• Immunology is the science of defense
• The immune system defends against infections, using different lines of defence
• It's a complex system of organs, cells and proteins which communicate and coordinate.
• A faulty immune system can result in diseases like allergies, autoimmunity, and cancers.

The Immune System - What and How?

• The immune system recognizes and fights diverse threats (microorganisms, toxins, and cancers)
• It repairs wounds.
• It differentiates between self (body) and non-self (everything else)
• It operates with two branches: innate (natural) and adaptive (learned) immunity.

The Immune System and Disease: A Two-Edged Sword

• The immune system defends against infection and tumors
• It plays a role in tissue regeneration and inflammation
• It's vital for recognizing and reacting to injuries and foreign grafts.
• A malfunctioning immune system can lead to various diseases, infections, allergies, autoimmune disorders, and difficulties in transplantation.

Defense Against Infection – Vaccination

• Effective vaccinations have dramatically reduced cases of various diseases
• Examples include diphtheria, measles, mumps, pertussis, polio, rubella, tetanus, and others
• Data is from US vaccination programs.

Pandemics and Immunology

• Pandemics highlight the importance of understanding immunology, as diseases are recurrent.
• Historical data on notable pandemics is provided

Advances in Immunology and Immunopharmacology

• Immunopharmacology studies immune regulation by drugs and therapies to modify immune function effectively.
• Advances include new approaches to treating disorders, allergies, cancer, and autoimmune diseases.

Immunopharmacotherapy

• Immunomodulators are drugs used to modify the immune system.
• Immunosuppressants (e.g., cyclosporin) are used for transplants
• Immunostimulants like vaccines (bacterial and viral) and immune checkpoint inhibitors are used in diverse applications.

Cell-Based Immunotherapy

• CAR-T cells, tumor infiltrating lymphocytes, engineered TCR therapy, and NK cell therapy are cell therapies for treating diseases
• These therapies are used in various applications.

Therapeutic Applications

• Autoimmune diseases involve antibodies against self-tissues, including thyroiditis, myasthenia gravis, type I diabetes, and glomerulonephritis
• Organ and tissue transplantation, such as kidney, heart, bone marrow transplantation, and pancreatic islet transplantation
• Cancer is another area where immune modulation is applied.

Summary

• Recognizes, combats various threats, including microorganisms and toxins
• Destroys pathogens and dysregulated self (such as cancers)
• Repairs wounds
• Has two main branches (innate and adaptive)
• Important for defending against pathogens and dealing with immune-related diseases.

Innate Immunity: Epithelial Barriers

• Epithelial barriers like skin and mucosa provide a physical defence against infection
• Physical and chemical components of these layers contribute
• Microbes and beneficial commensal bacteria are present.

Innate Immunity: Cells of the innate immune system

• The innate immune system employs different cells to combat infection.
• Included in this system are neutrophils, monocytes, macrophages, natural killer (NK) cells, dendritic cells, and mast cells.

Innate Immunity: Humoral Components

• Humoral components of the innate system include complement proteins and cytokines
• Complement proteins assist in neutralizing threats, and cytokines facilitate communication and regulation within the system

.### What is the Complement System?

• A system of proteins that helps the immune system by enhancing the ability of antibodies to destroy pathogens
• Proteins are primarily made by the liver
• They are mainly inactive until triggered by infection
• Some components are directly activated by pathogens, leading to rapid responses.

Complement System Function

• Complement involves activation through different pathways to produce C3b
• Early steps include inflammation, pathogen coating (opsonization)
• Late steps cover phagocytosis or lysis (destruction) by immune system cells.

Cytokines of the Innate Immune System

• Cytokines are soluble proteins that send signals from one cell to another
• Many immune cells use cytokines
• Includes TNF, interleukins, interferons, and growth factors such as colony-stimulating factors

Functions of Cytokines in Innate Immunity

• Cytokines control immune activity by influencing cell recruitment and other critical functions
• TNF and IL-1 play roles in fever, inflammatory responses, and regulating blood pressure
• Many other cytokines have crucial roles in immune responses.