Intro to immunology Flashcards by Annie Caldwell

Normal immune system is made up of these 3 things….

Physical barriers
Innate immunity
Adaptive immunity

How well did you know this?

Not at all

Perfectly

Physical barriers

Saliva 
- lysozyme
- IgA
- IgG
- lactoferrin 
Mucociliary escalator 
Gastric acid 
Normal flora
Physical flushing - urinary tract

How well did you know this?

Not at all

Perfectly

Examples of consequences of breached defences

Xerostomia
C diff infection
Cystic fibrosis
Burns

How well did you know this?

Not at all

Perfectly

Features of innate immunity

Rapid
Already present at birth
No memory - same response with re-exposure
Some specificity

How well did you know this?

Not at all

Perfectly

What does innate immunity detect?

Alteration from homeostasis

damage recognition - host
pathogen recognition - pathogen

How well did you know this?

Not at all

Perfectly

Where is the innate immunity found?

Within tissues

Within blood

How well did you know this?

Not at all

Perfectly

Cells of the innate immunity

NK cells
basophils
Neutrophils
eosinophils
Monocytes
Platelets
Macrophages
Dendritic cells
Mast cells

How well did you know this?

Not at all

Perfectly

Mechanisms of innate immunity

Inflammation 
Recruitment of immune cells
Activation of complement 
Opsonisation 
Phagocytosis
NK cytotoxicity

How well did you know this?

Not at all

Perfectly

What do cytokines do?

Regulate the nature, duration and intensity of the immune response
Form a method of communication between components of the immune system
Bind to specific receptors on target cells

How well did you know this?

Not at all

Perfectly

What predominately produces cytokines?

Macrophages

T helper cells

How well did you know this?

Not at all

Perfectly

Two types of cytokines

Pro-inflammatory 
- TNF-a
- IL-1
- IL-6
- Chemokines 
Anti-inflammatory 
- IL-10 
- TGF-B

How well did you know this?

Not at all

Perfectly

Pro-inflammatory cytokines cause…..

Fever
Recruit and activate other immune cells
vasodilation

How well did you know this?

Not at all

Perfectly

What does IFN-y activate?

Macrophages

How well did you know this?

Not at all

Perfectly

What does IL-3, IL-4, IL-5 and IL-13 activate?

Eosinophils

Mast cells

How well did you know this?

Not at all

Perfectly

What does IL-4, IL-5, IL-6 and IL-21 activate?

B cells

How well did you know this?

Not at all

Perfectly

What does IL-2, IL4, IL-12 and IFN-y activate?

T cells

How well did you know this?

Not at all

Perfectly

What causes inflammation of the innate immune system?

Detection of ‘foreign’ / breach in defences by pattern recognition receptors (PRRs)

How well did you know this?

Not at all

Perfectly

Features of inflammation and what causes each

Vasodilation 
- NO 
- Bradykinin 
- prostaglandins 
- TNF-a, IL-1
Increased vascular permeability 
- histamine
- nitric oxide 
- leukotrienes
Increased cell adhesion molecules 
- TNF-a, IL-1
Chemotaxis 
- CXCL-8
- neutrophil recruitment into the area
Increased sensitivity to pain 
- bradykinin

How well did you know this?

Not at all

Perfectly

Activation of complement

Activation of C3
- activated by
- alternative (pathogens)
- classical (combination of own antibodies bound to foreign antigens)
- lectin (free floating proteins in body attaching to pathogens)
Splits into C3a and C3b
- C3b splints into C5a and C5b
- C3a and C5a - anti-inflammatory toxins or protein which will affect mast cells to degranulate

C3a = inflammation 
C5a = chemotaxis

How well did you know this?

Not at all

Perfectly

What is C5b?

Membrane attack complex

How well did you know this?

Not at all

Perfectly

Activity of complement

Chemotaxis of phagocytes to sites of inflammation
- C3a, C5a
Opsonisation
- C3b, C4b
- preparation for eating (reduces repellent negative cell charge and increases no of binding sites for phagocytes)
Lysis of micro organisms
- C5b-9 complex
Maintain solubility of Ag / Ab complexes
- C3b, C4b, C2

How well did you know this?

Not at all

Perfectly

Main opsonins

Complement C3b, C4b
Antibodies
Plasma proteins - mannose binding lectin

How well did you know this?

Not at all

Perfectly

Phagocytosis is done against what?

Extracellular pathogens

How well did you know this?

Not at all

Perfectly

Two receptors on NK cytotoxicity

Activation
- if foreign pathogen / damaged cell
Inhibitory
- if normal cell

How well did you know this?

Not at all

Perfectly

Features of the adaptive immune system

``` Specific Delayed Immunological memory - faster responses to known antigen Humoral - antibody mediated - B lymphocytes Cell mediated - T lymphocytes ```

Two types of cells in the adaptive immune system

``` B cells (can lead to plasma cell) T cells ```

Where do B cells mature?

Bone marrow

Where do T cells mature?

Thymus

Where do B and T cells migrate to once matured?

Secondary lymphoid organs where they encounter antigens

What is an antigen?

A molecule capable of producing an immune response

Specificity of B cells - B cell receptor

Antibody attached to B lymphocyte

Specificity of T tells - t cell receptor

Within the T cells

T cell recognition of an antigen

Require presentation of antigen via MHC - CD4+ given by MHCII (antigen presenting cell e.g. macrophages) - CD8+ given by MCHI (all nucleated cells and platelets)

B cell recognition of an antigen

Recognise antigens directly via BCR (B cell receptor)

What is CD4+ given by and where is this found?

MCHII | antigen presenting cell e.g. macrophages

What is CD8+ given by and where is this found?

MCH1 | all nucleated cells and platelets

Processing of MHC1

Intracellular pathogens | Presented to MHC1 and highlights this to the immune system

Processing of MHC2

extracellular pathogens

What is an antibody?

A glycoprotein produced by B lymphocytes that binds antigens with a high degree of specificity and affinity

Two types of immune tolerance

Central tolerance | Peripheral tolerance

Central tolerance T cells types - thymus

``` Positive selection - can T cells recognise MHC? - if cant = destroyed Negative selection - does T cell interact too strongly with self antigens via MHC? - if cant = destroyed ```

Central tolerance B cells types - bone marrow

Self reacting BCR? | - if yes = destroyed

Features of peripheral tolerance

Monitoring of lymphocytes within secondary lymphoid organs and circulation Regulatory T cells

What do regulatory T cells do?

Recognise and destroy self reaction lymphocytes

Cytotoxic CD8+ cells release what?

IFN-y and TNF-a Cytotoxic granules ALSO - apoptosis via FasL-Fas interactions

Perforin + granzyme = what/

Apoptosis of target cell

What happens in perforin induced apoptosis?

Release of perforin and granzyme Perforin creates a hole/pore in cell membrane allowing granzyme to enter cell triggers apoptosis

What do helper T cells do? (CD4+)

``` Release cytokines to 'help' the activity of other immune cells Promote B cell antibody class switching e.g. IgM to IgG ```

Types of helper T cells (CD4+)

Th1 Th2 Th17

Th1 features

Intracellular pathogens - maximise macrophage and CD8+ activity - release IFN-y - inhibit TH2 response

Th2 features

Extracellular pathogens - release IL-4, IL-5, IL-13 - activate mast cells, basophils, eosinophils - class switching to IgE - inhibit Th1 response

Th17 features

Extracellular pathogens - PRO INFLAMMATORY - recruit neutrophils and macrophages via CXCL-8

What do regulatory T cells do?

Suppress CD4+ and CD8+ T cells Control the response to self antigens Secrete IL-10 and TGF-B

What do IL-10 and TGF-B do?

Anti-inflammatory | Suppress the immune response

B cells have humoral immunity via what?

Antibodies - FAB region - binds to antigen - FC region - communicates with immune cells

Immunoglobulin isotypes of B cells

``` Different heavy chains = different function IgM IgG IgA IgE IgD ```

What is IgM best at?

Activating complement

What can IgG do?

Cross the placenta

What happens to IgA?

It is contained in secretions

Features of IgE

Parasitic infections | Allergy

What are antibodies produced by?

B lymphocytes - plasma cells

Antibody mediated immunity phases

1. Lag phase - take a while for the specific immunity to kick in 2. If re-exposed - Very quick and very high risk in IgG

What is B activation done by?

T helper cells

Functions of antibodies

Immune complex formation Opsonisation Activating the cascade complement Antibody dependent cellular cytotoxicity (ADCC)

What does antibody dependent cellular cytotoxicity do?

Binds to target cells and initiates a non-phagocytic cell mediated destruction

Normal variation in immune function is seen in....

Pregnancy Neonates Elderly

Differences in an elderly persons immune function

``` Thymic involution Fewer naïve T cells Reduced ability for T cell expansion Reduced B cell development and diversity - diminished response to vaccination More dependent on innate immunity ```

Causes of secondary immune deficiency

``` Malnutrition - protein calorie malnutrition - zinc - iron Trauma Burns HIV DM renal failure asplenia malignancy Splenectomy Drugs - immunosuppressive, antirheumatic, antiepileptic, glucocorticoids, ciclosporin ```

Molecules of the innate immune system

Complement Interferon Cytokines Acute phase reactant

Receptors of the innate immune system

Pattern recognition receptors - toll like receptors - mannan-binding lectin

Molecules of the adaptive immune system

Immunoglobulins | Cytokines

Receptors of the adaptive immune system

TCR BCR MHC/HLA

What does TCR stand for?

T cell receptor

What does BCR stand for?

B cell receptor