Food
Allergies
Peanut Allergy
 Most prevalent food allergy in the US.
 1.5 million people suffer from the allergy.
 Exposure to a small amount of peanut
protein can trigger a potentially fatal reaction.
How small? A standard peanut has about 200
mg of protein, and studies have shown that
some people have an allergic reaction to just 2
mg—or around 1% of one peanut.
Peanut allergies do not cause problems
with the first exposure to peanuts.
The immune system develops
antibodies as a first reaction to the peanut
protein.
The next time the body comes in
contact with these proteins, the
antibodies attack the peanut proteins.
This induces the allergic reaction which
can be caused by direct contact, crosscontact and even inhalation.
With subsequent exposure, when the IgE
antibodies on the mast cells make contact
with the allergens, the mast cells release
chemicals such as histamine into the
bloodstream.
 The histamine causes such allergic
reactions as a runny nose, tearing eyes,
sore throat, diarrhea, skin rashes, or
difficulty breathing and swelling.
 A severe reaction is termed anaphylaxis.
Loss of consciousness or even death may
ensue if not treated.
Food Allergen Labeling and Consumer
Protection Act (FALCPA) 1/1/06 requires all
packaged foods comply with its food
allergen labeling requirements.
Eight major food allergens (peanut products
as well as milk, egg, fish, crustacean
shellfish, tree nuts, wheat and soybeans)
must be labeled in language that is easy to
understand.
Products exempt from
plain English labeling
rules: foods that are not
regulated by the FDA,
cosmetics and personal
care products,
prescription and
over‐the‐counter
medications or
supplements, pet food,
toys and crafts.
*The FDA has
exempted peanut oil
from being labeled as
an allergen.
Detecting the peanut
protein in food
Links to the
Real World
ELISA
Enzyme-Linked
Immunosorbant
Assay
• HIV, Mad Cow, SARS
• Biodefense
• Cancer treatment
• Drug and steroid testing
• Pregnancy / Reproduction
• GMO
ELISA
Antibody
Structure
Heavy
chain
Disulfide
bonds
Light
chain
ELISA
Antibody
Structure
The more antigen the darker the color
1
2
ELISA Kit
Workstation
Inventory
Reagents:
Yellow tubes
Violet tube (+)
Blue tube (-)
Green tube (PA)
Orange tube (SA)
Test samples (#1-#3)
Positive control
Negative control
Primary antibody
Secondary antibody
Lab Equipment and Supplies:
Microplate strips, pipettor, pipette tips,
transfer pipette, wash buffer, paper towels,
marking pen
3
2
1
1
1
1
ELISA
Enzyme-Linked
Immunosorbant
Assay
ELISA Kit
Results
What Are
The
Reagents?
And
What
Function Do
They
Perform?
PBS: Phosphate buffered saline – provides stable
buffered environment to maintain antibody
structure
Tween 20: Nonionic detergent – removes nonspecifically bound proteins to reduce background
and blocks protein binding sites on the
polystyrene
Microplates: Polystyrene – proteins absorb
(bind) by hydrophobic bonds to the polystyrene
What Are
The
Reagents?
And
What
Function Do
They
Perform?
Antigen: Chicken gamma globulin
Primary antibody: Polyclonal anti-chicken
antibody made by rabbits
Secondary antibody: Polyclonal anti-rabbit
antibody made by goats linked (conjugated) to
horseradish peroxidase (HRP)
Enzyme substrate: 3,3’,5,5’ –
tetramethylbenzidine (TMB) – a colorless solution
that when oxidized by HRP turns blue
Allergic Reaction
 The reaction is an abnormal immune
system response to things that are normally
harmless.
When one is allergic, the immune system
incorrectly identifies the substance as
harmful to one's body. (ie. certain foods,
medicines, plant pollen, or dust, are called
allergens.)
To protect the body, on first contact, the
immune system produces immunoglobulin
E antibodies which become attached to
mast cells.