Q:
What are the 4 major dichotomies of the immune system?

A:
* Innate vs Adaptive
* Antigen vs Antibody
* Humoral vs Cellular
* Mucosal vs Systemic

Q:
Who am I? I am a broadly directed protection. I have diverse components including; physical barriers, physiological processes, biochemical defences and celleular defences. I result from the genetic constituion of the host and I am not improved by repeated encounters with the same antigen.

A:
I am innate immuinty.

Q:
True or false? Antibodies bind to and destroy foreign cells.

A:
False. Antibodies are rarely directly beneficial (other than by neutralisation). Antibodies act as opsonins and also sensitise cells.

Q:
How are B cells 'immortalised' in the laboratory?

A:
They are fused with a malignant cell.

Q:
What are the two main functions of T cells?

A:
* Killing (cytotoxicity)
* Regulation (by cytokines)

Q:
What is the term for an antigen that leads to positive responsiveness?

A:
An immunogen.

Q:
What is the term for an antigen that leads to negative responsiveness?

A:
A tolerogen.

Q:
What is an antigenic determinant (epitope)?

A:
The specific portion of an antigen, to which an antibody or T cells receptor binds.

Q:
Under normal circumstances, approximately what percentage of serum proteins are antibodies?

A:
~20%

Q:
What are the 5 human antibody isotypes?

A:
IgG, IgM, IgA, IgE, IgD

Q:
What percentage of antibodies have kappa light chains?

A:
70%

Q:
What are the 5 types of antigen presenting cells?

A:
* Langerhans' cells
* Interdigitating cells
* Follicular dendritic cells
* B cells
* Macrophages

Q:
What is an antigen? 

A:
Any substance which activates lymphotcytes (positively or negatively) by interacting with the combining sites of T or B cell receptors.

Q:
What are some common antigens?

A:
* Microbial antigens (toxins)
* Blood group antigens
* Histocompatibility antigens (MHC Class I and II)
* Tumour antigens
* Autoantigens
* Allergens 

Q:
True or false? Antigenic determinants (epitopes) are made up of 150-200 animo acid residues.

A:
False. Antigenic determinants (epitopes) are made up of about 6 or 7 animo acids or sugars.

Q:
True or false? Each antibody chain is made up of a series of globular domains comprising 100-110 amino acids.

A:
True.

Q:
What are the features of IgM antibodies?

A:
* Pentameric structure with a J chain
* Monomeric IgM is found on the B cell surface
* Activates complements well
* Good agglutinator of antigen
* Prominent in the primary response
* Naive B cells produce IgM

Q:
What are the features of IgG Antibodies?

A:
* Abundant in serum and body fluids
* Longest half-life in serum (~23days)
* Prominent in the secondary response
* Good activator of complement
* Binds to Fc-gamma receptors on many cells
* Crosses the plancenta to provide protection to the newborn

Q:
What are the features of IgA antibodies?

A:
* Abundant in secretions, such as tears, saliva and secretions of the respiratory, gentiourinary and gastrointestinal tracts
* Exported by plasma cells as dimers with a J chain
* Actively transported across epithelium after binding to the polymeric Ig receptor
* A fragment of the pigR remains bound to secreted IgA, conferring resistance to proteolysis

Q:
What are the features of IgD antibodies?

A:
* Mainly found on the surface of naive B cells (which are positive for both IgM and IgD)
* Function remains unclear

Q:
What are the features of IgE antibodies?

A:
* Present in serum at extremely low concentrations 
* Involved in protection against multicellular parasites, and in allergic disease
* Receptors are found on mast cells, basophils and eosinophils
* Very short serum half-life

Q:
Is it the variable region of the heavy chain or the variable region of the light chain which is involved in antigen-antibody binding? 

A:
Both are involved.

Q:
What kind of bonds contribute to antigen-antibody binding?

A:
Multiple non-covalent bonds contribute to antigen-antibody binding.
 - Hydrogen bonds
 - Electrostatic forces
 - Van der Waals bonds
 - Hydrophobic bonds

Q:
What is the difference between antibody affintity vs. antibody avidity?

A:
The strength of a single ag-ab bond is known as the affinty of the antibody, but all antibodies have more than one antigen binding site. These sites 'work together' to provide stronger binding - the combined strength is known as the avidity of binding.

Q:
Which genes encode the heavy chain variable regions? 

A:
V, D and J genes.

Q:
Which genes encode the light chain variable regions? 

A:
V and J genes.