CORE Immunology

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of B cells in adaptive immunity?

Produce cytokines to activate immune responses

Kill infected host cells

Produce antibodies (correct)

Process antigens for T cell recognition

Which statement correctly distinguishes between cytotoxic T cells and NK cells?

NK cells require antigen recognition to act.

Cytotoxic T cells require MHC presentation for activation. (correct)

NK cells target only infected cells with specific antigens.

Cytotoxic T cells respond more quickly than NK cells.

What must happen for T cells to recognize an antigen?

The antigen must bind directly to T cell receptors.

The antigen must be processed and presented by B cells.

The antigen must be neutralized by antibodies first.

The antigen must be presented on MHC molecules. (correct)

What characterizes the MHC Class 1 pathway?

It is found on the surface of almost all body cells. Signup and view all the answers

How do T Cell Receptors (TCR) recognize antigens?

By binding to MHC molecules displaying processed antigens. Signup and view all the answers

Which cells are primarily involved in phagocytosis?

Macrophages Signup and view all the answers

What role does CD16 play in NK cell activation?

Binds to antibodies for ADCC Signup and view all the answers

What occurs when MHC class I molecules are absent from cells?

NK cells activate and destroy the target cell Signup and view all the answers

What are Pathogen Associated Molecular Patterns (PAMPs)?

Structures shared by many pathogens Signup and view all the answers

What is the primary function of macrophages?

To engulf bacteria and present antigens Signup and view all the answers

Which immune cell is primarily responsible for attacking parasites?

Eosinophils Signup and view all the answers

Which receptors recognize PAMPs in innate immunity?

Toll-like receptors (TLRs) Signup and view all the answers

How do neutrophils respond to pathogens?

By phagocytosing and activating bactericidal mechanisms Signup and view all the answers

What is the primary function of immature dendritic cells?

Activation of adaptive immunity Signup and view all the answers

What is the role of Natural Killer (NK) cells in the immune response?

To kill host cells that are infected with viruses Signup and view all the answers

What do lysosomes do during phagocytosis?

Fuse with phagosome and break down the microbe Signup and view all the answers

Which receptors are specifically mentioned for their role in NK cell activation?

Killer Immunoglobulin-like receptors (KIR) Signup and view all the answers

Opsonization primarily facilitates which process in the immune response?

Enhanced phagocytosis of difficult-to-capture microbes Signup and view all the answers

What type of immune response do PRRs promote upon detecting PAMPs?

Aiding in phagocytosis Signup and view all the answers

Which cell type is most abundant in the white blood cell population?

Neutrophils Signup and view all the answers

Mast cells play a crucial role in which type of immune response?

Allergic responses and inflammation Signup and view all the answers

What is the primary purpose of inflammation?

To promote tissue repair Signup and view all the answers

Which suffix is used to denote inflammation in medical terminology?

-itis Signup and view all the answers

Which of the following is NOT a symptom of inflammation?

Fever Signup and view all the answers

What initiates the recruitment of neutrophils during inflammation?

TNF alpha and IL-1 activation Signup and view all the answers

Which step involves the reduction of blood velocity in inflammation?

Vasodilation Signup and view all the answers

What is the role of E-selectin in neutrophil recruitment?

Facilitates neutrophil rolling Signup and view all the answers

In adaptive immunology, what is the initial response of a lymphocyte to an antigen called?

Activation Signup and view all the answers

Which phase of adaptive immunity involves the division of activated B or T cells?

Clonal expansion Signup and view all the answers

Which chemokines are involved in the recruitment of monocytes?

CCL2 and CCL7 Signup and view all the answers

What happens to T and B cells after the immune response is completed?

They undergo apoptosis Signup and view all the answers

What role do Danger Associated Molecular Patterns (DAMPs) primarily play in the immune system?

They activate the immune system during cell injury. Signup and view all the answers

What does C3b do in the complement system?

Attaches to microbe surfaces for phagocytosis. Signup and view all the answers

Which of the following cytokines is considered pro-inflammatory?

IL-1 Signup and view all the answers

What is a primary function of the complement system?

To promote inflammation and opsonization. Signup and view all the answers

Which of the following describes the function of C5a in the immune response?

It promotes vasodilation and increases vascular permeability. Signup and view all the answers

What characterizes the membrane attack complex formation?

It involves binding fragments that lead to cell lysis. Signup and view all the answers

Which statement about cytokines is true?

They have autocrine, paracrine, and endocrine actions. Signup and view all the answers

What type of proteins are primarily found in the complement system?

Soluble proteins Signup and view all the answers

Which of the following best describes cytokine networks?

They consist of complex interactions between multiple cytokines. Signup and view all the answers

What is a key characteristic of proteases in the complement system?

They can cleave other proteins to activate complement components. Signup and view all the answers

Study Notes

Introduction to Immunology

Immunology is the study of the immune system
The immune system defends the body against infection, tumours, and tissue damage
It also plays a role in tissue repair and inflammation
The immune system has mechanisms to recognize and respond to foreign substances, including microbes, grafts, and introduced proteins.

Roles of the Immune System

Defense against infections: vaccinations boost immune defenses against infections
Defense against tumours: Immunotherapy for cancer
Control of tissue regeneration & scarring: Repair of damaged tissues
Injuring cells and inducing pathologic inflammation: Immune responses cause allergic reactions and inflammation
Recognizing and responding to tissue grafts and newly introduced proteins: Barriers to transplantation and gene therapy

Problems with the Immune System

Immunodeficiency: Failure to respond to a substance/infection (e.g., malnutrition);
Allergy: Inappropriate response to foreign substances.
Autoimmune disorders: Inappropriate response to self leading to body attacking itself (e.g. lupus).
Transplant rejection: Appropriate but unwanted response to foreign substances.
Cancer: Altered self causing evasion of immune system.
Pregnancy: Causes toleration of non-self.

Physical & Chemical Barriers

Skin: Epithelial cells with tight junctions, fatty acids, low pH, enzymes, defensins, cathelicidin.
Gut: Longitudinal flow, enzymes (pepsin), alpha-defensins (cryptdins), normal microbiota.
Lungs: Longitudinal flow of air/fluid, mucus movement by cilia, pulmonary surfactant, beta-defensins.
Eyes/nose/oral cavity: Enzymes in tears and saliva (lysozyme), beta-defensins, histatins, cathelicidin.

Immune Responses

Innate Defenses: Immediate response before infection occurs. Recognizes infection via receptors that recognize common pathogen structures
Adaptive Response: Slow response stimulated by specific pathogens, reacts to a multitude of structures. It has a memory and is very specific.

Innate and Adaptive Immunity

Feature	Innate Immunity	Adaptive Immunity
Response time	Minutes/hours	Days
Specificity	Limited & broad	Highly specific
Diversity	Limited	Highly diverse
Memory response	No	Yes (faster, stronger responses)
Self/non-self discrimination	Perfect	Very good
Soluble components	Antimicrobial peptides/proteins	Antibodies
Major cell types	Phagocytes (macrophages, neutrophils), NK cells, dendritic cells	B cells, T cells

Types of Immune Cells

Leukocytes: Neutrophils, macrophages, T cells, B cells (each with specialized functions)
Phagocytes: Macrophages (patrol tissues, engulf bacteria), neutrophils (most abundant WBC, engulf bacteria), eosinophils (rare in blood, kill antibody-coated parasites), basophils (rare in blood, inflammatory mediators against parasites), mast cells (in tissues, inflammatory mediators for allergies).
Myeloid cells- monocytes (Kidney-bean shaped nucleus, phagocytosis, inflammatory mediators),
Agranulocytes- NK cells (kill infected host cells, chemical mediators).

Phagocytosis

Internalizing substances through engulfment
Steps: Binding, engulfment, killing and degradation

Opsonization

Coating a microbe with proteins to aid phagocytosis
Example: C-reactive protein (CRP)

NK Cells

Kill infected host cells without prior activation
Activated by missing MHC class I or by antibody coating of target cell

Cell Killing

Antibody-dependent cell-mediated cytotoxicity
Infected cells expressing microbial antigens are killed
Mechanism: similar to NK cells

Complement

Collection of soluble proteins aiding the immune system.
Prominent roles: promoting phagocytosis (Opsonisation), increasing inflammation, directly killing pathogens
Activation pathways: Classical, alternative, lectin pathways, resulting in lysis of cell membranes.

Cytokines

Soluble proteins produced by various cells
Roles: Autocrine (acts on producing cell), paracrine (local), endocrine (via blood)
Pleiotropy (multiple effects), Redundancy (complementary functions), Synergy (combined effects), Antagonism (opposing actions)
Examples: Interleukins (ILs), tumor necrosis factors (TNFs), interferons (IFNs).

Inflammation

Localized response (eliminate/wall off injury and dead cells) to promote tissue repair
Key symptoms include redness, heat, swelling, pain and functional impairment
Steps: PAMP/DAMP detection, mediator release, leukocyte recruitment, trigger elimination, tissue repair
Systemic (wide-spread) effects of localized inflammation involve body systems and organs.

Adaptive Immunity

Lymphocytes (B and T cells)
Antigen recognition
Clonal expansion and differentiation (generating effective cells)
Antigen elimination
Apoptosis: removing excess cells
Memory cells: faster responses in subsequent exposures

Antigen Presentation

MHC class I: Presents antigens from inside cells to cytotoxic T cells
MHC class II: Presents antigens from outside cells to helper T cells

B-cell Activation and Function

B-cells recognize antigens directly to activate
Produce antibodies to neutralize microbes or toxins
Antibody classes (isotypes): IgG, IgE, IgA, IgM, IgD (each with distinct roles)

T-cell Activation and Function

Helper T cells (TH): interact with other immune cells to coordinate immune responses, activate B cells, and promote inflammation
Cytotoxic T cells (TC): directly kill infected or abnormal cells

Studying That Suits You

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

Description

Explore the fundamentals of immunology, including the immune system's roles in defending against infections and tumors, as well as its involvement in tissue repair and inflammatory responses. Understand how the immune system identifies foreign substances and the issues that arise from its dysfunction, such as immunodeficiency and allergies.