Immunological hypersensitivity is an overreaction of the immune system to a specific substance and is probably the form of immunotoxicity most commonly observed in patients. This reaction essentially means lowering the threshold of clinical sensitivity to an antigenic stimulus.

When describing hypersensitivity, terms such as anaphylaxis, atopy and allergy are used.

a) Contact sensitivity and skin disorders . Occupational exposure to chemicals and other xenobiotics is one of the important causes of allergic reactions. Some common contact sensitizing agents are listed in the table below. 

b) Occupational asthma . Many substances can induce asthma. High molecular weight compounds, usually proteins, lead to classical IgE-mediated asthma. Low molecular weight substances can cause non-mediated IgE, its more persistent types. 

Occupational asthma often belongs to the latter category. Workers are sensitized as a result of exposure to concentrations of substances that are much lower than their official MPCs. Some common industrial substances associated with the development of occupational asthma are listed below.

Industrial chemicals leading to occupational asthma :
– Platinum salts
– Nickel salts
– Pyrethrum
– Diisocyanates
– Ethylene
diamine – Phthalic anhydrides
– Rosin
– Exotic wood dust

The table below shows a number of drugs that can induce negative pulmonary reactions, including allergic pneumonitis.

c) Allergic myocarditis . Allergic myocarditis should be suspected if the patient, along with the current allergic reaction to the drug, usually with eosinophilia, has electrocardiographic changes, a slightly elevated level of enzymes, cardiomegaly, and unexplained tachycardia. 

The diagnosis can be histologically confirmed by a transdermal transverse myocardial biopsy showing eosinophil-rich diffuse interstitial infiltrate with or without cell necrosis. Most cases of iatrogenic allergic myocarditis are due to methyldopa, sulfonamides and penicillin.

d) Classification of immunopathology according to Gell and Coombs . Immunopathological mechanisms involved in the development of hypersensitivity reactions, Gell and Coombs were divided into 4 types (I-IV). In one patient, more than one type of such disorder can be observed simultaneously. 

Allergic and pseudo-allergic reactions to drugs – the immune mechanism :

I. Drug allergy (negative immune reactions) : – Type I; IgE-mediated hypersensitivity (e.g., to penicillin, chymopapain and insulin anaphylaxis) – Type II: cytotoxic antibodies, often with complement precipitation (e.g. penicillin-induced hemolytic anemia) – Type III: immune complexes antigen-antibody and amplified, e.g. complement-response ( disease when administered to various drugs, drug fever and called pituitrinovogo powder inhalation allergic alveolitis) – Type IV: cell hypersensitivity (e.g., vyzy aemy neomycin paraben and contact dermatitis) 


II. Possible drug allergies (reactions suspected of having an immune mechanism): – Many iatrogenic skin reactions (e.g. erythema, erythema multiforme, maculopapular rash and fixed drug reaction) – Feverish mucocutaneous syndrome (erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, or Lyell’s syndrome) – Medicinal fever – Eosinophilic pneumonitis – Iatrogenic cholestasis and hepatitis – Interstitial nephritis – Lymphadenopathy  

III. Pseudo-allergic reaction to the drug (drug idiosyncrasy): – Anaphylactoid (similar to anaphylaxis) reaction (for example, to radiopaque agents) – Salicylate intolerance (sometimes due to a change in the formation or release of mediators) – Sensitivity to sulfite preservatives – Ampicillin .