99 immunoprophylaxis

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Immunomodulation therapy Treatment aimed at modulating the immune system ac-tivity of an individual. It is done either to in-crease the actual activity of the immune sys-tem (immunostimulation) or to suppress its activity (immunosuppression). The objective is immune normalisation, when activity of the immune system is restored to normal lev-els.

Immunopathology This is a sub-speciali-sation with the application of immunological techniques in the field to the practice of pa-thology. It studies the pathological changes occurring as a consequence of abnormal, in-creased (hypersensitive) or defective (immu-nodeficiencies) immune responses, their aetiology and diagnosis. Immunopathologi-cal (hypersensitive) reactions are nowadays classified according to Coombs and Gell into four types:

immediate or anaphylactic reactions (ana-1. phylaxis) mediated in humans by the IgE class of antibodies,cytotoxic type mediated by IgG or IgM an-2. tibodies against one’s own cellular or tis-sue antigens; the tissue damage is caused primarily by activated complement,immune complex reactions where soluble 3. immune complexes are formed and are deposited in various tissues and organs, such as the vascular system, the kidneys, the connective tissue or skin. Subsequent-ly, reactive oxygen species and lysosomal enzymes are released from neutrophils leading to tissue damage mediated by the immune complex deposition,delayed type hypersensitivity where T-4. lymphocytes, macrophages and certain cytokines are involved.

Recently, a fifth type of immunopathological response has been proposed with involve-ment of autoantibodies against the cellular receptors. These autoantibodies can influ-ence organ function via pathological stimula-tion (as agonists) or inhibition (as antago-nists). Thyrotoxicosis is an example of stimu-latory hypersensitivity in which the autoanti-bodies can falsely stimulate the TSH-receptors in the thyroid, whereas in primary myxoede-

ma (TSH-receptor blockade) or myasthenia gravis (acetylcholine receptor blockade), the autoantibodies inhibit function. The majority of autoimmune reactions belong to the sec-ond type of hypersensitivity according to this manner of classification.

Immunophilins Intracellular proteins with peptidyl-prolyl-cis-trans-isomerase activity specifically bind immunosuppressive drugs such as cyclosporine (CyA), FK506 and ra-pamycin. There is a specific cytosolic immu-nophilin for each of them (cyclophilin for CyA), which after binding to the relevant im-munosuppressant loses its enzymatic activity and thereby the ability to transmit the activa-tion signal from the T-lymphocyte receptor to the nucleus. This is the principle of their immunosuppressant activity.

Immunopotency The ability of a certain antigen molecule to serve as an antigenic de-terminant, thereby inducing the production of a specific antibody.

Immunopotentiation An increase in im-mune system efficacy (stimulation).

Immunoprecipitation This is the produc-tion of a precipitate upon the reaction be-tween a soluble antigen and its specific anti-body. It can occur in a solution or a semisolid (gel) environment (usually in agarose gel). The technique is carried out in a qualitative or quantitative manner. Using qualitative im-munoprecipitation, it is possible to determine the relationship between the amount of pre-cipitate and the antigen-antibody concentra-tion ratio. Huge excess of one of the two reac-tants can redissolve the immunoprecipitation (according to the precipitation curve or Heidelberger curve)

Immunoprophylaxis Prevention of a dis-ease by either vaccination that induces active immunisation, or by administering an im-mune serum (containing specific antibodies), or by administering specific active lympho-cytes, which induce passive immunity.