• Complications of Passive Immunotherapy

Antiserum can be raised in horses or other animals. Unfortunately, artificial passive immunization with animal antisera may cause severe complications, resulting from the immune response to the antibodies, which are of course foreign proteins. These include progressively more rapid elimination in 2-3 weeks (that reduced clinical effectiveness), and more severe complications as serum sickness and anaphylaxis. Serum sickness, a side effect that develops when the body eventually makes antibodies against the massive amounts of foreign protein found in the sera. Serum sickness (a model of type III hypersensitivity) follows repeated injections of foreign protein, leading to production of antibodies against the foreign (animal) immunoglobulins in antiserum used for passive immunization. Circulating immune complexes deposit in the kidneys, skin, and joints, which may be fatal. The danger of serum sickness increases with each successive exposure. Serum sickness may also follow passive immunization with human serum and human immunoglobulin preparations, but the danger is diminished because the proteins are less foreign. Passive immunization with a purified preparation of antibody specific for a single antigenic determinant further reduces the danger of serum sickness. Such uniformly specific antibody preparations are obtained by preparing monoclonal antibodies.

Another side effect of passive immunization with foreign immunoglobulins is sensitization – production of immunological memory following initial contact with an antigen (allergen), that stimulates the development of hypersensitivity (type 1). There are no symptoms, however until subsequent contact with the same allergen. Allergen exposure that elicits symptoms of hypersensitivity type 1 (anaphylaxis) in a sensitized host is termed the shocking dose.

Allergy desensitization (Bezredka’ method) is applied to prevent the development of anaphylaxis -generalized IgE-mediated allergic response. Allergy desensitization – introduction of small doses of allergen to eliminate IgE –mediated allergy .

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Besides MIBP for immunoprophylaxis and immunotherapy, there are preparations for diagnosis of infection. For diagnosis in vivo skin allergic tests (or allergological examination) are applied. MIBP for these tests are called allergens.

Skin allergic test – is an intradermal injection of antigen (allergen) to determine immunological sensitivity to a pathogen or its products. Allergen – is an antigen that elicits an allergic response (for example, PPD (purified protein derivative) from Mycobacterium tuberculosis cultures which is used for skin testing in tuberculosis). Skin test is an important tool for revealing the development of delayed type hypersensitivity and, therefore, for diagnosis of such infectious diseases where this type of allergic reactions develops.

The development of T effector cells to an antigen can often be revealed by intradermal challenge with that antigen. Such an intradermal challenge usually gives rise to erythema and induration, peaking at around 48 hours. This time course has led to the reaction being described as delayed-type hypersensitivity (type IV). In this type of hypersensitivity T lymphocytes, sensitized by an antigen (allergen), release lymphokines upon second contact with the same antigen. The lymphokines induce inflammation and activate macrophages. Delayed-type hypersensitivity is an allergic response produced by the cell-mediated immune system.