4th exam part 3

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Questions and Answers

What type of immunity is primarily responsible for removing specific pathogens?

Adaptive immunity (correct)

Innate immunity

Passive immunity

Non-specific immunity

Which cells are responsible for recognizing a single antigen and are activated by antigens?

Phagocytes

Macrophages and dendritic cells

Natural killer cells

B cells and T cells (correct)

What distinguishes MHC Class I molecules from MHC Class II molecules?

MHC Class I is found on all nucleated cells, while Class II is primarily on antigen presenting cells. (correct)

MHC Class I presents antigens to B cells, while Class II presents to T cells.

MHC Class I recognizes extracellular pathogens, while Class II recognizes intracellular pathogens.

MHC Class I is only expressed during an infection, while Class II is always expressed.

What is the primary effect of humoral immunity?

Production of antibodies by B cells Signup and view all the answers

Which of the following cells act as antigen presenting cells?

Dendritic cells and macrophages Signup and view all the answers

What characterizes T-independent antigens in the adaptive immune response?

Trigger B or T cells to proliferate and differentiate Signup and view all the answers

Which type of antigen is referred to as 'self' antigens?

Normal proteins produced by the body Signup and view all the answers

What is the primary role of MHC class I molecules in antigen presentation?

Bind endogenous antigens Signup and view all the answers

What distinguishes T-dependent antigens from T-independent antigens?

They require confirmation from helper T-cells Signup and view all the answers

Which process involves displaying endogenous antigens for immune surveillance?

Antigen presentation via MHC class I Signup and view all the answers

What is the main function of antigen presenting cells (APCs)?

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

Which type of antigen presentation is crucial for activating helper T-cells?

Presentation by MHC class II Signup and view all the answers

What type of molecules are primarily recognized as antigens by the immune system?

Proteins and some carbohydrates Signup and view all the answers

Which type of T cell is primarily responsible for activating B cells?

Helper T cells Signup and view all the answers

What is the primary function of cytotoxic T cells?

To induce apoptosis in infected or cancerous cells Signup and view all the answers

MHC class I molecules are recognized by which type of T cell?

Cytotoxic T cells Signup and view all the answers

What role do antigen presenting cells (APCs) play in T cell activation?

They present antigens using MHC class II molecules to Helper T cells. Signup and view all the answers

Which characteristic is unique to natural killer cells when compared to T cells?

They lack antigen receptors. Signup and view all the answers

What initiates the activation of B cells?

Cytokines produced by Helper T cells Signup and view all the answers

What type of molecules do cytotoxic T cells recognize?

MHC class I molecules Signup and view all the answers

What is the outcome of Helper T cell activation?

Activate macrophages and B cells Signup and view all the answers

Which marker is associated with Helper T cells?

CD4 Signup and view all the answers

Which cells are important for antibody-dependent cellular toxicity?

Natural killer cells Signup and view all the answers

What type of antigens are primarily presented by MHC Class I molecules?

Intracellular pathogen-derived antigens Signup and view all the answers

Which T cell type is activated by MHC Class II molecules?

Helper T cells Signup and view all the answers

What is the primary function of antigen presenting cells (APCs)?

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

During the T-dependent humoral response, what signal primarily prompts B cells to clone and differentiate?

Binding of specific antigens to B cell receptors Signup and view all the answers

Which of the following best describes the role of CD8 T cells?

They recognize and destroy infected cells Signup and view all the answers

What type of antigen do B cells bind directly to via their receptors?

Soluble antigens Signup and view all the answers

Which molecules act as 'key holders' in antigen presentation?

MHC molecules Signup and view all the answers

How do antigen presenting cells process pathogen proteins?

By hydrolyzing their proteins into small peptide fragments Signup and view all the answers

Which process is primarily responsible for non-specific recognition of pathogens in the immune system?

Pattern recognition by pattern recognition molecules Signup and view all the answers

What type of immune response is mounted against intracellular pathogens?

Cellular immune response Signup and view all the answers

Study Notes

Adaptive Immune Response

Adaptive immunity removes specific pathogens and remembers them for future encounters.

Division of Labor

Humoral immunity targets extracellular pathogens.
Cellular immunity targets intracellular pathogens.
Innate immunity recognizes Pathogen-Associated Molecular Patterns (PAMPs).

Adaptive Immunity

Adaptive immunity involves induced resistance to specific pathogen components.

Cells of the Immune System

The diagram shows a branching lineage of immune cells, starting from stem cells.
Lymphoid stem cells give rise to lymphocytes (B cells, T cells, and natural killer cells).
Myeloid progenitor cells give rise to granulocytes (neutrophils, eosinophils, basophils, and mast cells), monocytes, dendritic cells, and macrophages.

Phagocytic Cells

Non-specific phagocytic cells recognize PAMPs.
Examples include dendritic cells and macrophages.
These cells have multiple receptors to recognize different pathogens.
Specific phagocytic cells recognize only one shape.
T cells recognize antigens with T cell receptors.
B cells recognize antigens with immunoglobulin receptors.

Dual Nature of Adaptive Immunity

B and T cells originate from stem cells in the bone marrow.
Humoral immunity involves B cells maturing in the bone marrow (Bursa of Fabricius in chickens).
Antibody production is the key effect of humoral immunity.
Cellular immunity involves T cells maturing in the thymus.
T cells directly attack pathogens.

Adaptive Response

Adaptive immunity is triggered by antigens; two types are described.
T-independent antigens trigger a strong signal that leads to B or T cell proliferation and differentiation.
Pathogens are then attacked by the generated cells.
T-dependent antigens trigger a weaker signal which needs confirmation from helper T cells.
Helper T cells further stimulate B and T cells' growth and development for attacking pathogens.

Antigens

Antigens are molecules that trigger an immune response.
Some antigens are proteins, others are carbohydrates.
Antigens are often small, sometimes 5-9 amino acids.
Self-antigens are normal body proteins.
Non-self antigens are foreign.

Antigen Presentation

Antigen presentation involves presenting antigens on MHC molecules.
MHC (major histocompatibility complex) molecules are crucial for antigen presentation.

Quality Control

In cells, there's random sample testing and proteasome processes to identify and eliminate defective or dangerous cells.
The Major Histocompatibility Complex (MHC) is like a quality control system, checking for normal cells.

Summary

B and T immune cells work together to respond to threats.

Stop and Catch Up

Questions to prepare before moving on include details about different types of antigens.
Comparisons of MHC I and MHC II molecules

Immune cells

Immune cells are “preadapted” in the sense that their potential responses to different shapes are already defined.

Immune System Overview

Involves innate and acquired immunity components, reacting immediately to pathogens or later with adaptive immunity.

T Lymphocytes Overview

Cytotoxic T cells induce apoptosis in infected or cancerous cells that express MHC class I.
Helper T cells activate B cells and other immune cells.

T Lymphocytes Antigen Recognition

Helper T cells (CD4) respond to antigens presented by MHC class II molecules on antigen-presenting cells (APCs).

T Lymphocytes in B cell Activation

Helper T cells (Th cells) are crucial for activating B cells, leading to antibody production and B memory cells.

Humoral Response Summary

B cells create a clone of identical cells, which result in secreted antibodies
Primary response happens upon initial encounter with an antigen.
Secondary response happens upon subsequent encounter, with memory cells.

Natural Killer Cells

Natural killer (NK) cells are part of the innate immune system, lacking antigen specificity but recognizing antibody-coated cells or infected by viruses without MHC.

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Description

This quiz covers the key concepts of the adaptive immune response, including the division of labor between humoral and cellular immunity, and the various cells involved in the immune system. Explore how adaptive immunity removes specific pathogens and remembers them for future encounters. Test your knowledge on the roles of phagocytic cells and lymphocyte development.