Immunology

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of C5a in the complement system?

Forms pores in pathogen membranes

Increases vascular permeability and recruits immune cells (correct)

Activates T cells

Cleaves C3 to form C3b

Which components come together to form the membrane attack complex (MAC)?

C5a, C3, and C9

C3a, C5, and C6

C3b, C4, and C5

C5b, C6, C7, C8, and multiple C9 molecules (correct)

What is the potential outcome when the membrane attack complex (MAC) binds to microbial membranes?

Increase in bacterial replication

Direct cell death of the pathogen (correct)

Prevention of antigen presentation

Inhibition of the complement pathway

C3 convertase is formed from the cleavage of which complement component?

C3 Signup and view all the answers

What role do anaphylatoxins play in the immune system?

Increase inflammation and recruit immune cells Signup and view all the answers

What is the primary function of chemokines in the immune response?

To direct the migration of immune cells Signup and view all the answers

Which of the following are recognized functions of acute phase proteins?

Opsonisation of pathogens Signup and view all the answers

Which complement protein is known for its role in opsonization and as a blood marker for infection?

C-reactive protein Signup and view all the answers

What is the result of C3 convertase formation in the complement pathway?

Activation of the membrane attack complex Signup and view all the answers

What is the main role of anaphylatoxins in the immune response?

Attract immune cells to the site of infection Signup and view all the answers

Which of the following factors is NOT involved in the coagulation process of the immune response?

C3 convertase Signup and view all the answers

Which of these is a key function of the complement proteins?

Detection and destruction of pathogens Signup and view all the answers

The migration of immune cells in response to chemokines is known as what process?

Chemotaxis Signup and view all the answers

Which statement accurately describes the role of C5a in the immune response?

C5a promotes chemotaxis of immune cells to the site of infection. Signup and view all the answers

What is the primary function of natural killer (NK) cells in innate immunity?

Directly attacking and destroying virus-infected or tumor cells. Signup and view all the answers

During which pathway is the C3 convertase formed?

All of the above pathways can form C3 convertase. Signup and view all the answers

Which of the following functions is associated with anaphylatoxins?

Induction of systemic inflammatory responses. Signup and view all the answers

Which cell type is primarily responsible for the opsonization process in innate immunity?

All of the above. Signup and view all the answers

The complement system activates which critical immune response mechanism?

Cell lysis through the Membrane Attack Complex. Signup and view all the answers

What distinguishes opsonins from other immune proteins?

They enhance the uptake of pathogens by phagocytes. Signup and view all the answers

What is the role of acute phase proteins in the immune system?

Inflammatory response enhancement and pathogen marking. Signup and view all the answers

Which immune cells primarily recognize Class I MHC molecules?

CD8+ cytotoxic T cells Signup and view all the answers

What is the primary role of Major Histocompatibility Complex (MHC) molecules?

To present antigens to T cells Signup and view all the answers

What is required for T cell activation besides antigen recognition?

Costimulatory signals Signup and view all the answers

Which statement best describes the role of dendritic cells in the immune response?

They process and present antigens to T cells in lymph nodes. Signup and view all the answers

How does the Human MHC relate to its polymorphism?

It allows for the recognition of diverse pathogens. Signup and view all the answers

What type of T cell is primarily involved in helping B cells to produce antibodies?

CD4+ helper T cells Signup and view all the answers

Which co-stimulatory molecules are primarily involved in enhancing T cell activation?

CD80 and CD86 Signup and view all the answers

What characteristic of antigen-specific T and B cells is noted in immunology?

They are rare in the overall lymphocyte population. Signup and view all the answers

What is the primary function of Major Histocompatibility Complex (MHC) molecules in the immune response?

To present antigens to T cells for activation Signup and view all the answers

What must occur for B cells to be fully activated?

B cells require antigen binding and T cell help Signup and view all the answers

Which of the following describes a key function of T cell differentiation?

T cell differentiation prepares them to perform specific immune functions Signup and view all the answers

What is the function of Fc receptors on immune cells?

To recognize and bind the Fc region of antibodies Signup and view all the answers

Which of the following is necessary for T cell activation, in addition to antigen recognition?

Co-stimulatory signals from antigen presenting cells Signup and view all the answers

What is the main role of Th1 cells in the adaptive immune response?

To enhance phagocytosis by macrophages Signup and view all the answers

Which mechanism allows T cells to distinguish between self and non-self antigens?

Recognition of MHC-peptide complexes Signup and view all the answers

How does the structure of antibodies contribute to their function in the immune system?

Their structure allows for high specificity to antigens Signup and view all the answers

What is the role of Major Histocompatibility Complex (MHC) in T cell recognition?

It presents processed antigens to T cells. Signup and view all the answers

How do B cells primarily recognize antigens?

By binding to antigens circulating freely or on microbes. Signup and view all the answers

What occurs during T cell differentiation after antigen recognition?

T cells proliferate and differentiate into various effector cells. Signup and view all the answers

What is the function of the Fc region of antibodies?

It interacts with Fc receptors on immune cells to trigger immune responses. Signup and view all the answers

Which statement describes a necessary aspect of T cell activation beyond antigen recognition?

T cells need co-stimulatory signals to be fully activated. Signup and view all the answers

Which effector T cell type is primarily responsible for killing virus-infected cells?

Cytotoxic T cells (CD8+) Signup and view all the answers

What distinguishes regulatory T cells from other T cell types?

They suppress the activity of T cells and B cells. Signup and view all the answers

What type of cells present antigens to T cells as professional antigen presenting cells?

Dendritic cells Signup and view all the answers

What is the primary role of PD-L1/PD-1 inhibitors in cancer therapy?

To enhance T cell activity against tumors Signup and view all the answers

What is the main function of the chimeric antigen receptor (CAR) in CAR T cell therapy?

To recognize and bind to specific proteins on leukemia cells Signup and view all the answers

What is a potential downside of using monoclonal antibodies like Adalimumab in treatment?

They can lead to an increased risk of infections and tumors Signup and view all the answers

How are T cells genetically modified to express CAR in CAR T cell therapy?

Through the introduction of new DNA using a virus Signup and view all the answers

In which conditions is monoclonal antibody therapy, such as Adalimumab, typically used?

For various autoimmune and inflammatory conditions Signup and view all the answers

What does the concept of immunological tolerance primarily refer to?

The immune system's unresponsiveness to self-antigens. Signup and view all the answers

Where does the removal of cells bearing self-antigen receptors occur in the immune system?

In the bone marrow for B cells and in the thymus for T cells. Signup and view all the answers

Which mechanism ensures that the immune system does not attack self-antigens?

Anergy of self-reactive lymphocytes. Signup and view all the answers

How is the diversity of antigen receptors generated in lymphocytes?

By randomly recombining segments of receptor encoding genes. Signup and view all the answers

What happens to lymphocytes that bind their specific antigen during an immune response?

They proliferate and differentiate into effector cells. Signup and view all the answers

Which approach is an example of immunotherapy used to treat diseases?

Vaccination to enhance immune recognition of antigens. Signup and view all the answers

What is the primary role of antigen presenting cells (APCs) in the immune system?

To present antigens to T cells and activate them. Signup and view all the answers

What is a potential consequence of a loss of immunological tolerance?

Autoimmune diseases resulting from attacks on self-tissues. Signup and view all the answers

What is the main consequence of failing to delete self-reactive T cells in the thymus?

Development of autoimmune diseases Signup and view all the answers

How do tumor cells evade the immune response?

By expressing inhibitory ligands Signup and view all the answers

What is the role of checkpoint inhibitors in immunotherapy?

To block negative signals to T cells Signup and view all the answers

Which of the following is NOT a characteristic of regulatory T cells?

They can differentiate into effector T cells Signup and view all the answers

What is the primary purpose of using recombinant cytokines in immunotherapy?

To enhance immune cell production Signup and view all the answers

Which of the following conditions is associated with the failure to eliminate self-reactive T cells?

Rheumatoid Arthritis Signup and view all the answers

What impact does PD-L1 have on T cells?

It inhibits T cell activity Signup and view all the answers

What is a key feature of oncolytic virus therapy in cancer treatment?

It induces tumor cell apoptosis directly Signup and view all the answers

Study Notes

Innate Immune System

The innate immune system is a first line of defense against pathogens, acting quickly to limit infection.
It comprises physical and chemical barriers, cellular mediators (e.g., macrophages, neutrophils, dendritic cells, mast cells, T cells, B cells) and soluble mediators (e.g., cytokines, complement proteins, acute phase proteins).
Learning outcomes include understanding complement system activation and its key functions, the role of opsonins in host defense, the role of acute phase proteins, and the functionality of Natural Killer (NK) cells against infected cells.

Host Barriers to Infection

Physical/chemical barriers prevent pathogen entry (e.g., skin, mucus membranes).
Phagocytes engulf and destroy pathogens.
Cytokines regulate immune responses by directing cell migration.

Properties and Functions of Extracellular Innate Mediators

Various soluble mediators are part of the innate immune system.
Some mediators are present constantly (constitutive), while others are produced in response to infection (inducible).
Mediators directly kill pathogens or mark them for phagocytosis (opsonisation).
Mediators also recruit immune cells and activate immune cells/systemic inflammatory reactions.

Opsonins and Opsonisation

Opsonisation is the coating of a pathogen with opsonins, making it easier for phagocytes to recognise and engulf it.
Opsonins include antibodies and complement proteins.
Phagocytes possess specific receptors for opsonins.

Cytokines

Cytokines are small proteins mediating communication within the immune system.
Cytokines play critical roles in regulating the type, magnitude, and location of immune responses.

Chemokines and Cell Migration

Chemokines are a group of cytokines directing immune cell migration (chemotaxis) towards the source of the chemokine.
Cell response to chemokines depends on chemokine receptor expression on the cell surface.

Acute Phase Proteins

Synthesized in the liver in response to inflammation (inducible).
Sentinel cells release cytokines (e.g., IL-6), stimulating acute phase protein production.
Functions include: immune cell recruitment, pattern recognition (bacterial/fungal polysaccharides/glycolipids), and activation of the complement cascade. They also bind to and kill pathogens, enhancing uptake by phagocytic cells (opsonisation).
Acute phase proteins are used as non-specific indicators of infection/inflammation.

Complement System

The complement system is a cascade of proteins that enhance immune responses and destroy pathogens.
It may be activated through three pathways (classical – antibody, alternative – direct contact, lectin – carbohydrates).
Each pathway initiates a cascade resulting in a C3 convertase that cleaves C3 into opsonin C3b and anaphylatoxin C3a.
These actions increase vasodilation, vascular permeability, recruit immune cells, and enhance pathogen degradation by phagocytes.

Complement Activation

Complement systems can be activated via the classical, alternative, or lectin pathways.
They initiate with the recognition of the pathogen surface.
Complement activation leads to the creation of membrane attack complex (MAC), which creates pores in pathogen membranes causing lysis.

C3 Cleavage

All complement activation pathways trigger a cascade resulting in C3 convertase.
Cleaving C3 leads to the generation of opsonin C3b and anaphylatoxin C3a.
This promotes vasodilation, vascular permeability, immune cell recruitment and pathogen degradation by phagocytes.

C5a and the Membrane Attack Complex (MAC)

C5 convertase cleaves C5 to C5a and C5b.
C5a is an anaphylatoxin increasing vascular permeability and expression of adhesion molecules.
C5b initiates the formation of the MAC, which creates pores in the target cell membrane triggering lysis.

Anti-viral Defences

Key processes, such as interferons (viral response), and NK cells in identifying and eliminating stressed or infected cells. Type 1 interferons are produced by infected cells; they act on neighbouring cells to increase resistance to viral infection, and also act to enhance MHC-I expression and antigen presentation.

Natural Killer (NK) Cells

NK cells are important for recognizing and killing stressed cells, such as virally infected or cancerous cells.
These cells lack antigen-specific receptors.
NK cells make up around 10% of peripheral lymphocytes.

Next Steps

Adaptive immune system will be studied.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz focuses on the innate immune system, its components, and functions. It explores the role of physical and chemical barriers, cellular mediators, and soluble mediators in host defense. Understanding the activation of the complement system, opsonins, and the functionality of Natural Killer (NK) cells is essential for grasping the innate immune response.