immunology mw%% (+ Flashcards
1
Q
What are the first line of defense?
A
Physical Barrier:
- Skin
- Mucos.
2
Q
What are the 3 generic differences between adaptive and innate immune system?
A
- Specificity.
- Antibody production.
- Memory
3
Q
What are the major cells involved in innate and adaptive immune system?
A
- Innate: Phagocytes (macrophage, neutrophils), natural killer cells: NK cells play a major role in the host-rejection of both tumours and virally infected cells.
- Adaptive: lymphocytes.
4
Q
Describe the process of phagocytosis?
A
- Adherence
- ingestion
- formation of phagosome
- fusion with a lysomes to form a phagolysosomes
- digestion
- formation of residual body containing indegistable material and then discharge.
5
Q
Where is the origin of macrophages and what is their funcion?
A
- Made in bone marrow and are called monocytes and then macrophages in the tissues.
- Function is redness and recruitment and phagocytosis.
6
Q
Function of natural killer cells?
A
- Found in spleen (blood filter) and blood
- cause the cell to commit suicide by making a hole then releasing enzymes and chemicals contained within granule.
7
Q
Eosinophil
A
- Help combat parasitic infections.
- Involved in allergy and asthma.
- Granules contain many enzymes.
8
Q
Neutrophil
A
- Most abundant WBC
- Phagocytosis
9
Q
What is the function of mast cells?
A
- On encountering a parasite the mast cell dumps all it’s contents onto the parasite to kill it.
- The contents of the mast cell can also cause an allergic reaction in the host which if it is severe enough can cause anaphylactic shock.
- Anaphylaxis is a serious allergic reaction that is rapid in onset and may cause death.
10
Q
Basophil
A
- Least common of granulocytes (0.01 – 0.3%)
- Contain large cytoplasmic granules which obscure nucleus under microscope
- Cells store histamine in the granules. It increases the permeability of the capillaries to white blood cells, to allow them to engage pathogens in the infected tissues
- Often found in parasitic infections
11
Q
What is the complement system?
A
- it bridges a gap between adaptive and innate immunity.
- The complement response does not change over time
Has 3 activation pathways
- Promote phagocytosis of microbes (opsonisation)
- Stimulate inflammation – activate Mast Cells and Neutrophils
- Also stimulate activation of B Cells and Ab production
Note: all lead to the lysis of the target cell.
12
Q
What are cytokines?
A
Chemicals used by cells to communicate with other cells.
13
Q
What are the functions of Lymphatic System?
A
- Drainage of tissue(lymph vessels)
- Absorption and transport of fatty acids and fats
- Immunity
14
Q
Lymphatic Vessels
A
- Only carry fluid away from the tissues.
- Smallest are the lymphatic capillaries which begin in the tissue spaces as blind-ended sacs which are highly permeable
- Walls are composed of endothelium in which simple squamous cells overlap to form one-way valves
15
Q
Primary Lymphoid Organs
A
Places where blood cells are made and mature (receive their ‘early training) :
- Bone Marrow
- Thymus
16
Q
Secondary Lymphoid Organs
A
Sites of Lymphocyte activation (by antigens)
- Lymph node
- Spleen
- Toncil
17
Q
Lymph node function
A
- Filter and purify the lymph before it reaches the venous system
- 99% of antigen will be removed in the lymph node
- In response to antigen detection (APC)T cells and B cells are stimulated and adaptive immune response is initiated
- Maintain and produce B cells and house T cells
18
Q
Lymph node and lymphatic system pic
A
19
Q
Lymphatic drainage pic
A
20
Q
what is the function of T-cells?
A
T cells are responsible for cell mediated immunity(cytoxic or CD8+) and assisting B cells( Helper or CD4+ ).
T-cell selection:
- T cells must ‘learn’ not to recognise our own ‘self’ antigens.
- They must also be restricted to recognise Ag in association with our own MHC.
- The major histocompatibility complex is a set of cell surface proteins essential for the acquired immune system to recognize foreign molecules in vertebrates, which in turn determines histocompatibility
21
Q
Purpose of MHC Class l
A
- Found on virtually all nucleated cells.
- Presents ‘virally induced’ peptides to CD8+ T cells and trigger cytotoxic response.
22
Q
Purpose of MHC Class ll
A
- Found only on ‘Professional Antigen Presenting Cells’ (APCs).
- Presents exogenously produced Ag to CD4+ T cells (helpers)
- Activates macrophages and B cells
23
Q
Difference between T cell and B cell lympocytes in recognition of Antigen?
A
- B cells – recognise free organic antigen via B Cell Receptors (BCR)
- T cells need to be shown protein antigen in association with MHC
24
Q
What is the role of B cells in immunity?
A
- Mature into Plasma Cells
- Plasma cells are responsible for antibody (Ab) production.
- Express surface immunoglobulin (sIg) which is the antigen receptor for the B cell
25
what is self-tolerence?
The body's immune defenses do not normally attack tissues that carry a **self marker.**
26
T Helper Cells (Th)
* **Cannot kill** infected cells or pathogens
* **Activate** and direct other immune cells
* Essential in B cell Ab class switching
* Essential in activation and growth of Tc
27
Cytotoxic T Cells
* When exposed to infected / dysfunctional somatic cells Tc Cells release **perforin**
* Forms **pores** in the target cell
* Also release **Granzyme B**, a protease, that can enter target cells via the perforin-formed pore and induce apoptosis
28
T Cell Memory
* Memory T cells can arise from fully differentiated T cells or from T cells which are only partially differentiated – allowing potential for **further differentiation on re-exposure** to the antigen.
29
B Cell (and T cell) Tolerance
* Both B Cells and T Cells can be made **tolerant**, but it is more important to tolerize T cells than B cells because B cells cannot make **antibodies** to most antigens without the help of **T cells**.
* B cells which **recognise self Ag die** in the bone marrow by **apoptosis**
**Defintion:** a state of **unresponsiveness** of the immune system to substances or tissue that have the capacity to **elicit** an immune response in given organism. It contrasts with conventional **immune-mediated** elimination of foreign antigens
30
Antibody Structure pic
31
5 different classes of Antibody
**Immunoglobulins** (Ig) are the proteins with antibody activity- 5 classes
* **Primary response (IgM)**: Good at fixing compliment and opsonization (kill bacteria)
* **Secondary response (IgG**): Good opsonizer (crosses placenta)
* **Mucosal immunity (IgA)**: Protects mucosal surfaces, resistant to stomach acid (Neutralisation)
* **Allergy and helminth** infection (worm-like parasites) (**IgE**): can causes anaphylactic shock
* **IgD** – **No** known Ab function
32
Opsonisation
Opsonisation is a term that refers to an immune process bacteria are targeted for **destruction** by **phagocytes**. The process of opsonization is a means of **identifying** the invading particle to the **phagocyte**.
