Verzögert auftretende Symptome einer Soforttypallergie

[Diagnostics of alpha-gal syndrome : Current standards, pitfalls and perspectives]

α-Gal syndrome results from sensitization to the carbohydrate epitope galactose-α-1,3-galactose (α‑gal). The allergen occurs in mammalian meat and innards, but also in other foods and medical products of animal origin. Allergic reactions generally occur delayed after allergen intake with a latency period, depending on the individual tolerance threshold and the influence of cofactors. Details in the patient's medical history can help to establish the suspected diagnosis of α‑gal syndrome. Confirmation of the diagnosis requires the expertise of specialists, experienced with the implementation and interpretation of in vitro and in vivo diagnostic tests. Whereas skin prick testing with commercial whole-meat extracts often does not provide reliable results, allergen-specific IgE (α-gal) is generally detectable in affected patients. Cell-based tests such as the basophil activation test are currently only employed in an experimental setting. To evaluate, whether a sensitization is clinically relevant, an in-patient oral food challenge should be performed, using for example cooked pork or porcine kidney in addition to suspected cofactors.

Delayed immediate-type hypersensitivity to red meat and innards: current insights into a novel disease entity

The development of component-resolved diagnostics instead of whole extracts has brought about major advances in recent years. Particularly remarkable has been the identification of new disease entities based on the detection of IgE antibodies against specific individual components. In this context, delayed immediate-type hypersensitivity to red meat and innards plays a key role. This disorder is more common in German-speaking countries and likely still underdiagnosed. Affected individuals exhibit delayed type I reactions following the consumption of red meat or innards (responses to the latter are more rapid). All patients have IgE antibodies against the oligosaccharide galactose-α-1,3-galactose - alpha-gal. Those affected also have to avoid alpha-gal-containing drugs such as cetuximab or gelatin-containing colloidal solutions. Also referred to as alpha-gal syndrome, this condition is unique in that it is characterized by type I hypersensitivity to a sugar instead of a protein. Given that many patients have a history of recurrent episodes of acute urticaria or angioedema, dermatologists should be familiar with the alpha-gal syndrome.

Clinical spectrum of α-Gal syndrome: from immediate-type to delayed immediate-type reactions to mammalian innards and meat

The term α-Gal syndrome describes a novel IgE-mediated immediate-type allergy to the disaccharide galactose-α-1,3-galactose (α-Gal). Its classification as a syndrome is proposed on the basis of its clinical relevance in three different fields of allergy: food, drugs, and tick bites. The main focus of the present article is on α-Gal as an eliciting allergen in food allergy. It was recently shown that immediate-type allergies to pork kidney and other mammalian innards belong to the spectrum of α-Gal syndrome. These allergic reactions manifest as classic immediate-type allergies with a typical latency of under 1 h. The phenomenon of a delayed-onset immediate-type allergy with a latency of 3-6 h following ingestion of mammalian meat is considered pathognomonic for α-Gal syndrome. This clinically distinct type of presentation can be explained using the concept of food-dependent exercise-induced anaphylaxis (FDEIA). However, clinical observations and challenge testing in this constellation reveal that individual sensitivity in α-Gal patients is highly variable and which broadens our basic understanding of α-Gal syndrome.

Allergy to Red Meat: A Diagnosis Made by the Patient and Confirmed by an Assay for IgE Antibodies Specific for Alpha-1,3-Galactose

We report the first case of allergy to red meat observed in Ivory Coast. A 49-year-old male presented with pruritus. The diagnosis of allergy to red meat was confirmed by an assay for IgE antibodies specific for alpha-1,3 galactose. Interestingly, the disease was considered a spell to the patient who was suspected of being a sorcerer by the community.

IgE antibodies to alpha-gal in the general adult population: relationship with tick bites, atopy, and cat ownership

BACKGROUND

The carbohydrate alpha-gal epitope is present in many animal proteins, including those of red meat and animal immunoglobulins, such as cat IgA. Systemic anaphylaxis to the alpha-gal epitope has recently been described.

OBJECTIVE

To investigate and compare the prevalence of alpha-gal-specific (s)IgE and its associated factors in the general adult population from two separated (Northern and Southern) European regions (Denmark and Spain, respectively).

METHODS

Cross-sectional study of 2297 and 444 randomly selected adults from 11 municipalities in Denmark and one in Spain. Alpha-gal sIgE was assessed by ImmunoCAP to bovine thyroglobulin. Additional assessments included a panel of skin prick test (SPT) to common aeroallergens and epidemiological factors, including the history of tick bites in the Danish series.

RESULTS

The prevalence of positive (≥ 0.1 kUA /L) sIgE to alpha-gal was 5.5% and 8.1% in the Danish and Spanish series, respectively. The prevalence of sIgE ≥ 0.35 kUA /L was 1.8% and 2.2% in Denmark and Spain, respectively. Alpha-gal sIgE positivity was associated with pet ownership in both series and, particularly, cat ownership (data available in the Danish series). Alpha-gal sIgE positivity was associated with atopy (SPT positivity) in both series, although it was not associated with SPT positivity to cat or dog dander. Alpha-gal sIgE positivity was strongly associated with a history of tick bites.

CONCLUSIONS AND CLINICAL RELEVANCE

The prevalence of alpha-gal sIgE antibodies in these general adult European populations is similarly low. The presence of alpha-gal sIgE antibodies is associated with a history of tick bites, atopy, and cat ownership.

The allergic emergency--management of severe allergic reactions

Anaphylaxis is characterized by the sudden onset of acute allergic symptoms involving two or more organ systems. An acute allergic emergency is a challenge for physicians due to its life-threatening potential. The incidence of anaphylactic reactions has increased in recent years. Most frequent elicitors of mast cell and primarily histamine dependent anaphylactic reactions are food, insect venom or drugs. Allergic -reactions are graded into four groups according to the classification by Ring and Messmer; grade I is defined by the onset of cutaneous symptoms only whereas grade IV is characterized by cardiovascular shock as well as cardiac and/or respiratory arrest. The treatment of allergic reactions should be guided by the severity of the reaction. Initially an intramuscular epinephrine injection into the lateral thigh should be given if cutaneous, mucosal and cardiovascular/respiratory symptoms occur. Additionally, the patient should receive intravenous antihistamines and corticosteroids. For self-treatment in the case of an allergic emergency, oral antihistamines and corticosteroids should be prescribed to the patient.

Anaphylaxis: opportunities of stratified medicine for diagnosis and risk assessment

The risk to develop anaphylaxis depends on the sensitization pattern, the proportion of the involved immunoglobulin classes, the avidity and affinity of immunoglobulins to bind an allergen, characteristics of the allergen, the route of allergen application, and, last but not least, the presence of cofactors of anaphylaxis. To be able to calculate the risk to develop anaphylaxis and to anticipate the severity of the reactions under certain conditions, it is necessary to understand how all these factors interact with each other. Important progress for risk assessment in anaphylaxis is based on component-resolved stratified diagnostics, which allow to (i) determine a patient's sensitization pattern on a molecular basis, (ii) correlate clinical responses to defined sensitization patterns, and (iii) better identify cross-reactive allergens. Together with the increasing knowledge regarding the role and mode of action of cofactors of anaphylaxis, these data pave the way to unscramble the complex interactions determining the clinical relevance of sensitizations, the risk of anaphylaxis, and the severity of reactions. As a consequence, this understanding allows to better determine the individual risk in response to an identified allergen and results in more specific advices and education for our patients to prevent further life-threatening anaphylactic reactions.