What is a protein domain? What is an immunoglobulin domain?

Amino acid sequence in a peptide that defines a region that regularly folds the same way and performs a predictable function, such as the catalytic site of an enzyme

            Amino acid sequence in an antibody peptide that always folds into the same functional structure

What is a cytokine?

A protein that is made by cells of the immune system. Some cytokines can boost the immune response and others can suppress it.

Heavy chain & light chain variable & constant

Constant domains are coded by the inherited genome, variable domains coded by recombined DNA

The heavy and light chain variable domains bind antigen because their sequence was selected out the B-cell repertoire

Fc  fragment mediates effector activity

Effector molecules bind to Fc and cause some effector process to happen, such as complement-mediated lysis, phagocytosis and cell-mediated cytotoxicity

Blocking ligand receptor interactions, targeting cells for destruction or something else, acting as signaling agonists

Block by binding ligand or block by binding receptor

What sorts of signaling effects can antibodies have?

Crosslinking receptors to activate cell division or other responses, including apoptosis

• After antibody binding via Fab sites, complement factors attach to Fc and form the membrane attack complex to form a hole in the target cell.
• IgG and IgM.
• Complement factors.

What 3 problems are seen when mouse monoclonal antibodies are used as therapeutic or diagnostic agents in humans? What approach was taken to fix these problems?

• Short half-life, failure to trigger effector function, human anti-mouse antibodies.
  
• Genetic engineering approach to make chimeric antibodies that are partially human sequence and less immunogenic.

What is a chimeric antibody? What advantages do chimeric antibodies have?

• A genetically engineered antibody with human constant domains and mouse variable domains.
  
• Less immunogenic.

An attempt to minimize the mouse sequence by only cloning the mouse CDR sequence into a human variable domain.

What 3 developments have led to the possibility  of making fully human antibodies by genetic engineering?

1. Discovery of human variable region genes
2. successful expression of them in E. coli
3. invention of phage display method

If you were  determined to use mice to make  fully human monoclonal antibodies, what would you have to do to the mice?

Exchange natural mouse immunoglobulin genes for the human genes

What is serum therapy and when was it used? Is it still used, and if so, for what purpose? What is post-exposure prophylaxis?

• The intravenous use of serum from a patient who is assumed to have immunity to the infectious disease of the patient. Primarily before the era of antibiotics.
  
• Today only for emergencies such as acute lethal toxin or virus exposure such as rabies, botulism.
  
• Prevention of infection after known exposure to the agent.

What are the 5 immunoglobulin classes? Which class is the first produced in a primary immune response? Which class is involved in histamine release? Which class is most abundant in serum?  Which class protects the fetus?

• IgA, IgD, IgE, IgG, IgM.
• IgM
• IgE
• IgG
• IgG

Transgenic mice & phage display

What is the most effective way of making a drug using monoclonal antibodies to treat viral infections?

Making an artificial polyclonal mixture of monoclonal antibodies

Which cytokine is associated with rheumatoid arthritis and how?

TNF-alpha accumulates in joints where it causes inflammation

In Table 1, what are the two most frequent general disease indications for approved monoclonal antibodies?

Cancer -6, immune-4, CV -2, infectious disease-1

Cause direct or indirect destruction of cancer cell, by targeting the cell of its blood supply

How can you use radioactive elements and antibodies together to kill cancer cells? How can you use toxins and antibodies together to kill cancer cells?

Tightly bind a radionuclide or toxin to the antibody without blocking the Fab binding site

functional Fc region

• VEGF causes a blood supply to form that nourishes the tumor
• Avastin

A plain antibody molecule with nothing attached to it and requires natural Fc-mediated effector function to have a therapeutic effect

When naked antibodies kill cancer cells via effector cell cytotoxicity, how does the killing actually happen?

Cytoxic and phagocytic cells bind the Fc region and kill or engulf the cancer cell

What are bispecific antibodies and how could they be used? What  effector cell population  would be the best target for bispecific antibodies?

• Bispecific antibodies have 2 different antigen specificities
• A cytotoxic effector cell.

• Cytokine storm (cytokine release syndrome)
• Fc receptor can be mutated to prevent activation of immune effector cells and cytokine secretion

Neutralizing toxins and blocking ligand receptor interactions

Fv (engineered), Fab (natural or engineered), Fab2 (natural or engineered)

More screening capacity can give better specificity and affinity; haptens, toxic drugs and other toxic substance can be used as antigens

• Producing single chain Fv molecules and then grouping them into dimers and trimers
  
• increasing avidity increases crosslinking activity

Stability (half-life) & immunogenicity

Rapid clearance from the circulation

Presence of the Fc region allows binding of neonatal Fc receptor that prevents destruction of antibody

What modification can be made to increase the serum half-life of antibodies and their fragments? How does it work?

• Addition of polyethylene glycol polymers
• raises size above kidney filtration threshold and lowers immungenicity

Stimulation of both antibody and T-cell

• Antigenic protein is bound to Fc while Fab targets specific T cells
• attach antigen to another part of the antibody molecule to allow Fc-mediated uptake