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The Immunopathology of Hypersensitivity Reactions
Vincent A. Marinkovich, M.D.
Clinical Associate Professor, Stanford Medical School,
Overactivity of the immune system, either allergy (IgE) or hypersensitivity
(non-IgE) is responsible for more illness than is generally appreciated, even by
the medical profession. The least understood are the non-IgE mechanisms which
involve either immune complex formation (type III of Gell and Combs) or direct
killer T-cell involvement (type IV). Type III reactions may be localized with a
large deposition of antigen at a focal point where immune complexes are formed
and tissue damage ensues including necrosis. This is termed the Arthus reaction.
A systemic dissamination of antigens will provoke a systemic inflammentory
reaction which is most closely modeled by the well studied acute and chronic
serum sickness reaction. Serum sickness was identified as the constellation of
symptoms which followed the aadministration of antitoxins (antisera given for
infectious disease before the advent of antibiotics) which were derived from
non-human sources, most often horses. Chronic serum sickness was observed when
otherwise heaalthy subjects were given repeat doses of antisera experimentally
over relatively short periods of time. The symptoms observed in spontaneous and
experimental serum sickness included fatigue, rash, cognitive changes, myositis,
arthritis, headache, weight-loss, cardiovascular symptoms etc., which are often
seen during heavy chronic exposure to fungal spores. The dynamic nature of
circulating immune complexes, their complexity, their rapidly changing
exquilibrum patterns aaand their pathogenicity must be appreciated before the
clinican can properly interpret the patterns of illnes his patients’ describe.
The best simple test identifying and thereby allowing the avoidance of serum
sickness is a specific IgE test to a panel of high exposure antigens including
fungi, food and occupational antigens.