ANAPHY: U12.2 Lymphatic System & Immunity (Immunity)

Immunity

Body’s defense against infections, foreign particles, and abnormal cells

Innate & Adaptive Immunity

2 Types of Immunity

Innate Immunity

Type of immunity; provides immediate, nonspecific defense against a broad range of pathogens

Adaptive Immunity

Type of Immunity; Develops over time and is specific to particular pathogens, featuring a memory component for rapid response to previously encountered antigens

Specialized immune response that provides long-lasting defense by developing targeted responses to specific pathogens

Immediate Defense Mechanism, Non-Specific Defense, No Memory Component

3 Characteristics of Innate Immunity

Immediate Defense Mechanism

One of the characteristics of innate immunity; Innate immunity acts within minutes to hours upon detecting pathogens

Minutes to Hours

Time innate immunity usually acts within

Non-Specific Defense

One of the characteristics of innate immunity; Targets general pathogen features (e.g., cell walls) without needing specific antigen recognition

No Memory Component

One of the characteristics of Innate Immunity; Does not retain information about past infections

Physical & Chemical Barriers

2 Main Components of Innate Immunity

Physical Barriers

One of the main components of innate immunity; Skin and mucous membranes block pathogen entry

Skin & Mucous Membranes

What do the physical barriers of innate immunity include?

Chemical Barriers

One of the main components of innate immunity; Acidic secretions, lysozyme in saliva, and antimicrobial peptides

Acidic secretions, lysozyme in saliva, and antimicrobial peptides

What do the chemical barriers of innate immunity include?

Macrophages, Neutrophils, Natural Killer Cells

3 Cells of Innate Immunity

Macrophages

One of the cells of innate immunity

Engulf and digest pathogens, dead cells, and debris, playing a key role in innate immunity and inflammation; Widely distributed in tissues, especially in areas like lymph nodes, spleen, and lungs

Neutrophils

One of the cells of innate immunity

Most abundant type of white blood cell, specializing in rapid response to infections, particularly bacterial; Engulf and destroy pathogens through phagocytosis and release toxic enzymes to kill microbes.

Natural Killer (NK) Cells

One of the cells of innate immunity

Type of lymphocyte involved in the destruction of virus-infected cells and abnormal cells (e.g., tumor cells) before adaptive immunity is activated

NK cells recognize cells lacking “self” markers (MHC I) and release cytotoxic chemicals that induce apoptosis in target cells

What is the mechanism of action of Natural Killer (NK) Cells?

Inflammation

Body’s immediate response to infection or injury, aimed at containing pathogens, promoting healing, and alerting the immune system

Vasodilation, Increased Permeability, Recruitment of Immune Cells

3 Stages of Inflammation

Vasodilation

First stage of inflammation; Blood vessels widen to increase blood flow, causing redness and heat

Increased Permeability

Second stage of inflammation; Allows immune cells and proteins to leave the bloodstream and enter affected tissues, leading to swelling

Recruitment of Immune Cells

Third stage of inflammation; Neutrophils and macrophages migrate to the site of injury to engulf pathogens

Redness (rubor), heat (calor), swelling (tumor), and pain (dolor)

4 Classic Signs of Inflammation/Hallmarks of Inflammation

Redness (Rubor)

One of the 4 Classic Signs of Inflammation/Hallmarks of Inflammation

Due to increased blood flow to the area

Heat (Calor)

One of the 4 Classic Signs of Inflammation/Hallmarks of Inflammation

Elevated temperature from blood flow, aiding in pathogen destruction

Swelling (Tumor)

One of the 4 Classic Signs of Inflammation/Hallmarks of Inflammation

Fluid buildup as blood vessels become more permeable

Pain (Dolor)

One of the 4 Classic Signs of Inflammation/Hallmarks of Inflammation

Chemical mediators and swelling stimulate nerve endings

Specificity & Memory

2 Characteristics of Adaptive Immunity

Specificity

One of the characteristics of adaptive immunity; Recognizes and responds to specific antigens

Memory

One of the characteristics of adaptive immunity; Retains a memory of pathogens, enabling quicker responses upon re-exposure

Cell-Mediated Immunity & Humoral Immunity

2 Major Components/Types of Adaptive Immunity

Cell-Mediated Immunity

One of the Major Components/Types of Adaptive Immunity

Involves T-Cells that attach infected cells directly

Humoral Immunity

One of the Major Components/Types of Adaptive Immunity

Involves B-cells and antibodies that target pathogens in body fluids

Antigens

Substances that the immune system recognizes as foreign; they stimulate an immune response

Major Histocompatibility Complex

What is MHC?

MHC I & MHC II

2 Types of MHC

MHC I

One of the types of MHC; Found on all nucleated cells; displays endogenous antigens to cytotoxic T-cells

MHC II

One of the types of MHC; Found on antigen-presenting cells; presents antigens to helper T-cells

Present antigens on cell surfaces, helping T-cells identify infected cells

Role of MHC molecules in adaptive immunity?

Helper T-Cells (CD4+), Cytotoxic T-Cells (CD8+), Regulatory T-Cells (Tregs)

3 Types of T-Cells in Adaptive Immunity

Helper T-Cells (CD4+)

One of the types of T-Cells in Adaptive Immunity

Coordinate the immune response by activating other immune cells, including B-cells and cytotoxic T-cells

Cytotoxic T-Cells (CD8+)

One of the types of T-Cells in Adaptive Immunity

Directly attack and kill virus-infected and cancerous cells.

Regulatory T-Cells (Tregs)

One of the types of T-Cells in Adaptive Immunity

Suppress immune responses and help maintain immune tolerance, preventing autoimmune diseases

Antigen Presentation, Co-Stimulation, Differentiation

3 Stages in the Process of Activation of T-Cells

Antigen Presentation

First Stage in the Process of Activation of T-Cells

T-cells are activated when an antigen-presenting cell (APC) presents an antigen on its MHC molecule

Co-Stimulation

Second Stage in the Process of Activation of T-Cells

Additional signals from APCs are required to fully activate T-cells, ensuring specificity

Differentiation

Third Stage in the Process of Activation of T-Cells

Activated T-cells differentiate into helper, cytotoxic, or regulatory subtypes, each with specific immune roles.

Bone Marrow

Where do B-cells mature and develop the ability to recognize specific antigens?

Plasma Cells & Memory B-Cells

What will B-Cells differentiate into upon encountering an antigen?

Plasma Cells

One of the differentiated B-Cells

Produce antibodies to neutralize pathogens

Memory B-Cells

One of the differentiated B-Cells

Retain antigen memory for faster responses upon re-exposure

Y-shaped proteins with 2 heavy chains and 2 light chains, with variable and constant regions

Structure of Antibodies

Variable & Constant Region

2 Regions of Antibodies

Variable Region

One of the regions of antibodies

Binds to specific antigens, allowing precise recognition of pathogens

Constant Region

One of the regions of antibodies

Determines the antibody class and mediates immune functions (e.g., opsonization)

Neutralization, Agglutination, Complement Activation

3 Main Functions of Antibodies

Neutralization

One of the main functions of antibodies

Bind to pathogens, preventing their entry into cells

Agglutination

One of the main functions of antibodies

Clump pathogens together, aiding in their removal

Complement Activation

One of the main functions of antibodies

Triggers the complement system to destroy pathogens

IgG, IgA, IgM, IgE, IgD

5 Classes of Antibodies/Immunoglobulines (Ig)

IgG

One of the classes of antibodies

Crosses the placenta, providing passive immunity to the fetus

IgA

One of the classes of antibodies

Found in mucosal areas like saliva, tears, and breast milk; protects mucosal surfaces

IgM

One of the classes of antibodies

First antibody produced in response to infection; effective in complement activation

IgE

One of the classes of antibodies

Involved in allergic reactions and responses to parasitic infections

IgD

One of the classes of antibodies

Primarily functions in B-cell activation

Complement System

Group of plasma proteins that assist antibodies in clearing pathogens

Classical & Alternative Pathway

2 Pathways of Activation of the Complement System

Classical Pathway

One of the pathways of activation of the complement system

Triggered by antibodies bound to antigens

Alternative Pathway

One of the pathways of activation of the complement system

Directly activated by pathogen surfaces

Opsonization, Membrane Attack Complex (MAC), Inflammation

3 Functions of the Complement System

Opsonization

One of the functions of the complement system; Coats pathogens to enhance phagocytosis.

Membrane Attack Complex (MAC)

One of the functions of the complement system; Creates pores in pathogen membranes, leading to cell lysis

Inflammation

One of the functions of the complement system; Releases histamine and attracts immune cells to infection sites

Primary Response

The initial response to a new antigen, slower as B-cells and T-cells are activated and differentiated

Secondary Response

Faster and stronger response due to the presence of memory cells from the primary response

Memory B-cells and T-cells

Allow for a rapid and robust response upon re-exposure to an antigen

Active & Passive Immunity

2 Types of Acquired Adaptive Immunity

Active Immunity

One of the types of acquired immunity

Developed when the body produces its own antibodies in response to exposure

Natural Active Immunity & Aritificial Active Immunity

2 types of Active Immunity (Type of Acquired Immunity)

Natural Active Immunity

Type of active immunity; Occurs when one is exposed to pathogens naturally

Artificial Active Immunity

Type of active immunity; achieved through vaccination

Passive Immunity

Type of acquired immunity

Obtained through the transfer of antibodies from another source

Natural Passive Immunity & Artificial Passive Immunity

2 types of Passive Immunity (type of Acquired Immunity)

Natural Passive Immunity

Type of passive immunity; Antibodies are transferred from mother to child via the placenta or breast milk

Artificial Passive Immunity

Type of passive immunity; Antibodies are administered via injection for immediate protection.

Vaccination

Introduction of an antigen (often a weakened or inactive form of a pathogen) to stimulate an immune response without causing illness

Mimic infection, leading to the development of memory cells without the risk of severe disease

How do vaccines work?

Live-Attenuated, Inactivated, Subunit/Conjugate, mRNA Vaccines

4 Types of Vaccines

Live-Attenuated Vaccine

Type of vaccine; Weakened form of the pathogen

Inactivated Vaccine

Type of vaccine; Killed pathogen

Subunit/Conjugate Vaccine

Type of Vaccine;

Specific parts of the pathogen (e.g., proteins)

mRNA Vaccines

Type of vaccine; Use synthetic mRNA to instruct cells to produce pathogen proteins

Innate immunity provides the first line of defense, while adaptive immunity provides targeted responses

How does innate and adaptive immunity collaborate?

Cytokine

Proteins that coordinate the immune response, recruiting and activating immune cells

Small proteins secreted by immune cells to regulate immunity, inflammation and hematopoiesis

Interleukins, Interferons, Tumor Necrosis Factors (TNF)

3 Types of Cytokines

Interleukins

Type of cytokine; Promote communication between WBCs

Interferons

Type of cytokine; Released in response to viral infections; interfere with viral replication

Tumor Necrosis Factors (TNF)

Type of cytokine; involved in inflammation and can induce apoptosis in infected cells