When your body is exposed to a substance the immune system deems a threat, like bee sting venom at Plant Atlanta, your body can respond with hypersensitivity. There are four main types of hypersensitive reactions. Below we review what a hypersensitive reaction is and how to recognize the four types.
What Is a Hypersensitive Reaction?
When you have a hypersensitive reaction, it means your body has an extreme or unnecessary immune response to an antigen. The different types of reactions are based on the type of antigen, the immune response the body generates and how quickly the body responds.
Allergies are a form of hypersensitivity, but an allergic reaction refers to the signs and symptoms that are experienced while a hypersensitivity refers to the immunological process that occurs in the body.
Type 1 Hypersensitivity Reaction
A type 1 hypersensitivity reaction produces an immediate response after exposure to an antigen. During this type of reaction, the body produces an antibody called Immunoglobulin E (IgE).
There are two stages of a type 1 reaction: the sensitization stage and the effect stage. The sensitization stage is when the antigen is encountered but no symptoms occur, and the effect stage is when the antigen is re-encountered and a response is produced.
Type 1 reactions can be triggered by:
- Food products: nuts, shellfish, soy, etc.
- Animal sources: cats, dogs, bee stings, etc.
- Environmental sources: dust, mold, latex, etc.
- Allergic conditions: allergic rhinitis, allergic asthma, conjunctivitis, etc.
Signs of a type 1 reaction include:
- Flushing
- Hives
- Itching
- Swelling
- Rash
- Stomach cramps
- Nausea/vomiting
- Wheezing
- Shortness of breath
- Loss of consciousness
Type 2 Hypersensitivity Reaction
A type 2 reaction involves both IgE and IgM antibodies. During a type 2 reaction, healthy cells can die as they respond to antigens, which can cause long-term damage to the cells and tissues, leading to:
- The blood disorder immune thrombocytopenia.
- Autoimmune hemolytic anemia.
- Autoimmune neutropenia.
- Grave’s disease.
Type 2 reactions typically result after exposure to medications such as:
- Penicillin.
- Thiazides.
- Cephalosporins.
- Methyldopa.
Type 3 Hypersensitivity Reaction
With a type 3 reaction, antigens and antibodies cause complexes in the skin, blood vessels, joints and kidney tissues, resulting in tissue damage.
This type of reaction can be caused by:
- Drugs containing proteins from other organisms, like antivenins.
- The autoimmune drugs infliximab.
- Animal sources like tick bites and insect stings.
The reaction can lead to:
- Serum sickness.
- Lupus.
- Rheumatoid arthritis.
- Small-vessel vasculitis.
- Henoch-Schönlein purpura.
Type 4 Hypersensitivity Reaction
Type 4 reactions are cell-mediated, which means they are controlled by T cells rather than antibodies.
Type 4 reactions can be caused by:
- Poison ivy.
- Certain metals.
- Drugs such as antibiotics or anticonvulsants.
During this reaction, a person could experience:
- Contact dermatitis.
- Tuberculin-type hypersensitivity.
- Granulomatous-type hypersensitivity.
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