The antiserum that is mostly used for the treatment and prevention of diseases such as rabies, diphtheria, tetanus, pneumonia, and venomous snake, are derived from animals. These antisera that are loaded with antibodies are also rich in proteins that can cause sensitivity to some persons. Serum sickness occurs when an individual reacts to these proteins present in therapeutic antiserum and elicits a type II hypersensitivity reaction.

Mechanism of the reaction

Antiserum is commonly used in the form of antitoxins or antivenoms for medical purposes. But for some people, their body recognizes the proteins as harmful antigens. In response to that, the immune system produces antibodies in about 6-10 days. They bind with the antigens and form antigen-antibody complexes that deposit in tissues or vascular linings. These complexes attract polymorphonuclear (PMN) leukocytes that release enzymes that cause tissue damage. The joints and kidneys are particularly susceptible. Joints are frequently tender, and renal manifestations include excretion of proteins and some red blood cells. There may be mild to severe cardiac involvement. In some cases, there might be paralysis causing Guillain-Barré Syndrome.

There is usually a skin rash and itching which makes it similar with Type I allergies, but the mechanism is distinct from true anaphylaxis. But anaphylactic shock may also arise. Various medications like penicillin may also cause a serum-sickness like reaction but without the formation of immune complexes.

What your Doctor can do for you

The reaction in serum sickness is similar to an allergy. Therefore, for the condition to be ruled out, blood tests must be carried out. Antihistamines and topical corticosteroids are generally used for the treatment of serum sickness. NSAIDs may be used to relieve the joint pain. Plasmapheresis may also be an option to remove the immune complexes from the blood.

What you can do

Serum sickness can only be prevented by avoiding the agent if you have had immune reactions over it in the past.