Immunity

Adaptive Immunity

• is the 3rd line of defense

• The triggering of specialized cells to specifically target antigens of pathogens with the aid of antibodies to create a specific immune response.

• Can be activated quickly or prolongedly

• Dendritic B & T- Lymphocytes are the main cells

Key components:

1. Specificity: Targeted response to distinct antigen

2. Diversity: Recognition of a wide range of antigens

3. Memory: Rapid and robust response to previously recognized antigens

4. Self & non-self Recognition: able to identify antigens on body cells and foreign antigens

Innate immunity

• The second line of defense

• Also known as inflammation, the fast-acting response to damage of cells through the use of chemical mediators and phagocytic WBCs

Antigen

A substance on or in a pathogen that inflicts a immune response

Antibody

• Known as immunoglobulins (Ig)

• Produced by differentiated B-lymphocytes

• Will detect and bind to specific antigens

• IgA, IgM, IgE, IgD

Immune cell origins: Lymphoid progenitor

• Natural Killer cells

• T-Lymphocytes

• B-Lymphocytes

Immune cell origins: Myeloid progenitor

• Monocytes

• Dendritic cells

• Granulocytes

• Mast cells

T-Lymphocytes

• Target cancer and viruses

• Mature and differentiate in the Thymus

• Have specific receptors that bind to antigens

• Requires direct contact with an antigen and then will proliferate and differentiate into:

1. cytotoxic T-Lymphocytes (direct destruction of antigen-carrying pathogens)

2. Helper T-Lymphocytes (enhances humoral & cell-mediated immune responses)

3. Suppressor T-Lymphocytes (inhibits humoral & cell-mediated responses to not be excessive)

• Attack the cells that are infected

Humoral Immunity

• adaptive immunity that involves that antibodies within the bloodstream

• IgG is the most abundant immunoglobulin and only able to cross placenta

Cell-mediated immunity

• Cytotoxic T-Lymphocytes are the main part of this

• The recognition of cells carrying non-self antigens

Cytotoxic T-Lymphocytes

• Attack tumour and viruses

• Direct destruction of antigen carrying pathogens

• Express CD8

Helper T-Lymphocytes

• Enhance humoral and cell-mediated immune responses

• Express CD4

Suppressor T-Lymphocytes

* Inhibit humoral and cell-mediated immune responses so they don’t become excessive

Dendritic cells

• When they come into contact with a pathogen, it will act as a phagocyte and bring the antigens displayed to T-Lymphocytes for identification

• APC’s (antigen presenting cells)

B-Lymphocytes

• mature in the bone marrow

• Migrate to the lymph tissues and are activated when in contact with an antigen, which causes the B-lymphocyte to differentiate into antibody-secreting plasma cells

• They identify specific antigens based off a specific receptor, which causes adaptive immunity involving specific antibodies to be produced

• The antibodies are known as immunoglobulins

• Attack on the outside of the cell through antibodies

• Known as effector cells

Natural Killer (NK) Cells

• A large granular lymphocyte

• When they come into contact with cells they deem a threat (cancer, virus) they will exert their cytotoxic effect through attacking and killing that cell

Granulocytes

• Neutrophils (target bacteria)

• Esophils (Target parasites)

• Basophils (enhance mast cells, important in allergic reactions)

Monocytes

• Will differentiate when in the presence of a antigen into a macrophage

• Macrophages will engulf the pathogen and display its antigen so T & B-Lymphocytes can identify it

Active (adaptive immunity) Natural

* from infection

Passive (adaptive immunity) maternal

• comes from mother to fetus through placenta barrier

• Only IgG is small enough to transfer

Artificial (adaptive immunity) Passive

* antibody transfer

(immunoglobulins given to someone with rabies)

Artificial (adaptive immunity) Active

* getting immunization

Apoptosis

• programmed cell death after pathogen is destroyed

• The ones that don’t are called memory cells

Clonal Expansion

* the producing of more cells

Clonal selection

* selects what B-cells antibodies best fit the invader and then those cells will go through clonal expansion and then create monoclonal antibodies or the same

Major Histocompatibility Complexes (MHC)

or

Human Leukocyte antigens

Traps an antigen within the cell and transports it to the cells surface so T-Lymphocytes can identify it

• MHC I : found on nucleated body cells and detected by CD8 cytotoxic T-Lymphocytes

• MHC II : found on APC’s and is detected by CD4 Helper T-Lymphocytes

Neutralization

* The bind of a antigen to a antibody resulting in the pathogen unable to infect other cells

clusters of differentiation (CD’s)

* T-lymphocytes express clusters of differentiation (CD’s) which our membrane surface molecules used too determine specific function of T-cell subtype

Toxoids

are antigens in the form of exotoxins that have been chemically modified not to cause harm and can be injected to bind to T-Lymphocytes to enlist a immune response

BRM’s Biological response-modifying drugs

• These drugs can enhance or restrict the bodies immune response to disease

The three mechanisms:

1. enhancement or restoration of the hosts immune system defences against the tumour

2. direct toxic effects on the tumour cells which causes them to lyse or rupture

3. adverse modification of the tumours biology which makes it hard for those cells to reproduce

immunomodulating drugs (IMD)

* a class of BRMS use to treat autoimmune disorders

Antibody titire

* how many antibodies are needed per antigen which is why we may need booster shots