Exam 2 Immunology

Many unknown and uncontrollable factors

Disadvantage of In vivo

In vivo

Within a living body

Provides the most natural experimental condition

Advantage of In vivo

In vitro

Within an artificial environment

Artificiality, cannot fully replicate complex physiological conditions

Disadvantage of In vitro

Easy to handle, genetically well-characterized, rapid breeding cycle, well-characterized immune system, similar to the human immune system, and many inbred strains available

Why are mice mostly used as experimental animals

Reduce genetic variation

What do inbred strains do

Syngenetic animals

Genetically identical members of the same species

Genetically identical

Homozygous at more than 99% of all loci in the genome

Approximately 500

How many inbred strains of mice are there

Adoptive transfer experiments

Allow In vivo examination of isolated cell populations

Transgenic animals

Carry genes that have been artificially introduced

Foreign or transgenes

Introduced to embryo

Inserts into a random site and can have multiple insertions

Cons of transgenic genes

Knockout and knock in genes

Replace a normal gene with a nonfunctional version or an alternate version

Conventional transgenic approaches (random insertion, multiple insertions)

Knockout and knock in genes over come the cons of

The genetic manipulation of Embryonic stem cells (ESCs)

Knock in and out genes rely on what

Integrate into germ line cell chromosomes

Transgenes must do what to become a heritable trait

injection and integration into pronucleus of the egg

Transgenes are introduced in an embryo by

Screened by PCR, then injected into early blastocysts, and implanted into a pseudopregnant female and allowed to gestate

What happens to manipulated ESCs

Nude (Athymic) mice

Homozygous for Foxn1nu element (nu), a recessive gene on chromosome 11

They have no immune system, hair, and have a vestigial thymus (no T cells)

What is wrong with nude/athymic mice

They have no mature functional B or T cells, although immature cells are still present

What is wrong with SCID mice

SCID mice

Due to mutation in gene for protein kinase, DNA activated catalytic polypeptide (PRKDC)

RAG Knockout mice

Specific loss/impairment of RAG1 or RAG2 gene

No T or B cells

What is wrong with RAG knockout mice

B, T, and NK cells

Mice with RAG and IL2RG gene mutations are deficient in

Primary cell culture, cell lines, and hybrid cell lines

The 3 major sources of cells

Have been obtained from their normal environment, have not been manipulated, and represent the normal situation as much as possible

Advantages of primary cell culture

Finite life span and heterogeneous population

Disadvantages for primary cell culture

Normal cells isolated directly from blood, lymph, or lymphoid organs

Primary cell culture

Populations of cultured tumor (cancerous) cells that divide indefinitely

Cell lines

HeLa (Henrietta lax) cells

Example of cell lines

Immortal, so virtually unlimited supply; homogeneous

Advantages of cell lines

Since cancerous, there may be abnormal genetic characteristics that do not represent the normal situation

Disadvantages of cell lines

Population of cells derived from a cell made immortal by fusing a B or T cell with a cancerous version

Hybrid cell lines

Displays traits associated with normal B or T cells, such as antibody production or cytokine production

Advantages of hybrid cell lines

Due to random chromosome loss, one cannot control which traits remain in final product

Disadvantages of hybrid cell lines

A detergent called polyethylene glycol

To fuse the B or T cell with a cancerous version what is often used

Plasmacytoma cell

Cancerous plasma cell in mice

Myeloma cell

Cancerous plasma cell in humans

Heterokaryon

Cell with two different nuclei

Hybridoma cell

Heterokaryon once it has undergone random chromosome loss

1 normal and 1 cancerous B or T cell, polyethylene glycol (detergent), Heterokaryon, Hybridoma cell

Steps of Hybrid cell lines

Monoclonal antibody

The product of a single B cell hybridoma line

Single-specificity Ab

A monoclonal antibody produces mass quantities of what

The immunologically active regions of an immunogen that bind to receptors on lymphocytes or to secreted antibodies

An epitope is

The N-terminal region

B cells respond to

The Carboxy (C)-terminal region

T cells respond to

B and T cell epitopes

The areas B and T cells bind to are called

That are free in solution in their native conformation

B cells recognize antigen and immunogens where

Highly accessible sites on cell surface

B cell epitopes are what compared to T cell epitopes

Processed peptides associated with MHC molecules that are presented on the surface of APCs (antigen presenting cells)

T cells only recognize

Not restricted to exposed sites

T cell epitopes are not restricted to what like B cell epitopes

Hydrophilic amino acids on the protein surface that are accessible to membrane bound or free antibody when the protein is in its native conformation, lipids (if complexed to protein or polysaccharide), no requirement of MHC molecules

B cell epitope details

Only recognize processed peptides, MHC molecules required to display processed antigen

T cell epitope details

Small molecules that are antigenic but not immunogenic

Haptens

Most drugs and hormones

What functions as haptens

Anit-hapten, anti-carrier, hapten-carrier (antibodies to the conjugate of hapten and carrier)

The three classes of antibodies

Anti-hapten

Which antibody class represents the major fraction

A foreign substance that is recognized by the specific immune system

Antigen

A foreign substance that induces a specific immune response

Immunogen

The ability to be bound by the final products of a specific immune system

Antigenicity

The ability to induce the production of antibodies or T cell activation

Immunogenicity

Also antigenic

All molecules that are immunogenic are

Not also immunogenic aka haptens

All molecules that are antigenic are

Foreignness, molecular size, chemical composition and complexity, and susceptibility to antigen processing and presentation

Factors that influence immunogenicity

The greater genetic disparity

The greater the phylogenetic distance

The greater the immunogenicity when substances are transferred from one species to another

The greater the genetic disparity

Cytochrome C and Collagen

These two are not immunogenic because they highly conserved across diverse species

100,000 daltons or greater

Very immunogenic molecules are around what size

Less than 5,000 to 10,000 daltons

Poor immunogenic molecules are around what size

Proteins, and then polysaccharides (2nd most potent)

The most potent immunogens are

Lipids and nucleic acids

These macromolecules are not typically immunogenic unless coupled to a polysaccharide

Atleast two different amino acids

In order for a protein to be immunogenic it must have what

Aromatic acids

What tends to increase complexity in proteins

Atleast two different sugars

In order for polysaccharides to be immunogenic t must have what

They are not immunogenic

Proteins of a single amino acid and polymers of a single sugar are not what

Monocytes, macrophages, dendritic cells, and B cells

Phagocytic cells and what leukocyte that present using MHC II are

Ingestion and digestion of soluble macromolecules

Endocytosis

Ingestion and digestion of insoluble materials

Phagocytosis

Only peptides are processed for presentation, polymers of D-amino acids cannot be processed, and large molecules are readily phagocytized than small molecules

Limits for antigen processing and presenting

a substance that acts to enhance or prolong specific immune responses when used in combination with specific vaccine antigens

Adjuvant

May prolong antigen persistence, may enhance costimulatory signals necessary for stimulation of B or T cells, may induce granuloma formation, may stimulate PRR signaling

Ways adjuvants enhance the immune response

Granuloma

Macrophage rich mass of cells

Gamma globulins or immunoglobulins

Antibodies are commonly called

25,000 daltons each

Light chains weigh how much

50,000 daltons each

Heavy chains weigh how much

150,000 daltons all together

How much does the antibody monomer weigh in total

Interchain disulfide bonds

What holds the chains together

408-614 amino acids in length

How long are the heavy chains

216 amino acids in length

How long are the light chains

Multiple myeloma

Cancer of plasma cells

Called myeloma protein, indistinguishable from normal antibody, accounts for 95% of the serum immunoglobin in patients and specific for one antigen, and most patients secrete excess light chains not bonded to heavy chains.

Role of myeloma proteins

Bence-Jones proteins

Excess light chains not bonded to heavy chains

Injecting mineral oil into peritoneal cavity (MOPC mineral oil induction of plasmacytoma cells)

Plasmacytoma can be induced in mice by

Either 2 kappa or 2 lambda chains. Never 1 of each

A single antibody always has two of what

The N-terminal

Considered the variable region of a antibody

The carboxy (C)-terminal

Considered the constant region of an antibody

The constant region

The class of antibody is determined by