Type III Hypersensitivity

Question 1

What type of hypersensitivity is Type III hypersensitivity?

Answer 1

Immune complex mediated

Question 2

What is Type III hypersensitivity induced by?

Answer 2

Antibody-antigen complexes formed in circulation with later deposition into organs or blood vessels resulting in tissue damage

Question 3

What is the harmful response of Type III hypersensitivity caused by?

Answer 3

Complement activation and release of neutrophils and C3b that ingest and destroy the antibody-antigen complex

Question 4

Types of antigens that can cause Type III hypersensitivity

Answer 4

Exogenous and endogenous

Question 5

Exogenous antigen examples

Answer 5

Environmental or foreign protein, bacteria, virus, like a gluten allergy or serum sickness

Question 6

Endogenous antigen examples

Answer 6

Individual forms antibodies against components of self resulting in autoantibodies like drug-induced lupus

Question 7

What medications can cause drug-induced lupus?

Answer 7

Hydralazine, procainamide, isoniazid

Question 8

Symptoms of drug-induced lupus

Answer 8

Arthralgia, fever, malaise, myalgias, swollen lymph nodes

Question 9

Labs from drug-induced lupus

Answer 9

Elevated ANA titer, SS-DNA, ESR

Question 10

Serum sickness time of onset

Answer 10

5-10 days after exposure to antigen

Question 11

Symptoms of serum sickness

Answer 11

Fever, swollen lymph nodes, arthralgias, dermatitis, vasculitis

Question 12

Arthus reaction

Answer 12

Localized type III reaction, typically to an organ like kidneys, joints, skin

Question 13

Agents known to cause serum sickness

Answer 13

Animal serums from polyclonal antibodies, bee venom, cefaclor, ciprofloxacin, insulin, iron dextran, IVIG, monoclonal antibodies, PCNs, sulfonamides

Question 14

Treatment of serum sickness

Answer 14

Removal of the offending agent.

If that doesn’t work, can use corticosteroids and immunosuppressive agents in severe cases