Two galactose-α-1,3-galactose carrying peptidases from pork kidney mediate anaphylactogenic responses in delayed meat allergy.

BACKGROUND: Serum IgE antibodies directed at galactose-α-1,3-galactose (α-Gal) are associated with a novel form of delayed anaphylaxis occurring upon consumption of red meat or innards. Pork kidney is known as the most potent trigger of this syndrome, but the culprit allergens have not yet been identified. The aim of this study was the identification and characterization of pork kidney proteins mediating delayed anaphylactic reactions through specific IgE to α-Gal. METHODS: A cohort of 59 patients with specific IgE to α-Gal was screened by immunoblot for IgE-reactive proteins in pork kidney. Proteins were identified by peptide mass fingerprinting. Isolated proteins were assayed in ELISA and ELISA inhibition, basophil activation and skin prick test. RESULTS: Several IgE-binding proteins of high molecular weight (100- >200 kDa) were detected in pork kidney extracts by immunoblot using patient sera and an anti-α-Gal antibody. Two major IgE-binding proteins were identified as porcine angiotensin-I-converting enzyme (ACE I) and aminopeptidase N (AP-N). Reactivity of patient sera and anti-α-Gal antibody to both proteins was abolished by carbohydrate oxidation. The α-Gal IgE epitopes were resistant to heat denaturation. Pork kidney extract, isolated ACE I, and AP-N were able to activate patient basophils and elicit positive responses in skin prick tests. CONCLUSION: Two cell-membrane proteins carrying α-Gal epitopes were identified in pork kidney. For the first time, isolated meat proteins were shown to induce basophil activation in patients with delayed anaphylaxis to red meat providing further confirmation for the clinical relevance of these α-Gal-carrying proteins.

Febrile ulceronecrotic Mucha-Habermann disease.

The Mucha-Habermann disease is an inflammatory disease of the skin and is a variant of pityriasis lichenoides et varioliformis acuta. We describe the case of a 64-years-old woman who was admitted for erysipelas of the face. Despite treatment, evolution was marked by the appearance of a necrotising ulcerative area in the centre of the erysipelas associated with local oedema and headache. A skin biopsy revealed a pityriasis lichenoides et varioliformis acuta. Corticosteroids led to a rapid stabilisation of lesions, and after 6 months the patient shows only a small area of frontal hypopigmentation. The aetiology remains uncertain. There is no established standard treatment. We would like to draw attention of the medical and surgical specialists to this rare disease. The diagnosis should be considered in a necrotic lesion associated with rapid expansion of systemic and peripheral cutaneous signs. Diagnosis must be considered to avoid unnecessary debridement and extensive scars.

Evaluation of two new recombinant guinea-pig lipocalins, Cav p 2 and Cav p 3, in the diagnosis of guinea-pig allergy.

BACKGROUND: Guinea-pigs, classical laboratory animals now often kept as pets, regularly elicit important allergic reactions. Two guinea-pig allergens have been described previously to some extent; however, biomolecular and immunological data are lacking. OBJECTIVE: To identify major guinea-pig allergens, produce them as recombinant proteins and define their allergenic potential and clinical importance in allergic patients. METHODS: Protein extracts were prepared from various guinea-pig tissues and allergens were purified by ion exchange chromatography. The N-termini of two immunoglobulin E (IgE)-reactive proteins were determined and degenerate primers were designed for cDNA amplification by RT-PCR. Allergenic properties of recombinant proteins were assayed by immunoblotting, ELISA and mediator release assays. Specific IgE were quantified in the sera of 26 guinea-pig-allergic patients. RESULTS: Major IgE-reactive proteins were detected in submaxillary and harderian gland extracts. Two proteins were identified and the cDNAs were cloned. The 17 kDa protein expressed in the harderian gland corresponds to the previously described Cav p 2. The 19 kDa protein, Cav p 3, is a new allergen expressed in the submaxillary gland. Recombinant Cav p 2 and Cav p 3 were recognized by IgE antibodies from 65% and 54% of guinea-pig-allergic patients, respectively. Both proteins demonstrated equivalent allergenic activity in the mediator release assays. CONCLUSION AND CLINICAL RELEVANCE: Two major guinea-pig allergens, Cav p 2 and Cav p 3, have been characterized and produced as recombinant proteins. Combined to guinea-pig serum albumin, the new allergens proved to be valuable in the component-resolved diagnosis of guinea-pig allergy.

IgE antibodies of fish allergic patients cross-react with frog parvalbumin.

BACKGROUND: The major allergens in fish are parvalbumins. Important immunoglobulin (Ig)E cross-recognition of parvalbumins from different fish species has been shown. Recently frog parvalbumin alpha has been found to be responsible for a case of IgE-mediated anaphylaxis triggered by the ingestion of frog meat. The aim of this study was to investigate whether IgE antibodies of fish allergic persons cross-react with frog parvalbumin and to appreciate its clinical relevance. METHODS: The sera of 15 fish allergic patients and one fish and frog allergic patient were tested by IgE-immunoblotting against frog muscle extract. Sera were tested against recombinant parvalbumin alpha and beta from Rana esculenta. Skin prick tests were performed in selected patients with recombinant frog parvalbumin. Ca(2+) depletion experiments and inhibition studies with purified cod and frog recombinant parvalbumin were done to characterize the cross-reactive pattern. RESULTS: Fourteen of the sera tested had IgE antibodies recognizing low molecular weight components in frog muscle extract. Calcium depletion experiments or inhibition of patient sera with purified cod parvalbumin led to a significant or complete decrease in IgE binding. When tested against recombinant parvalbumins, three of 13 sera reacted with alpha parvalbumin and 11 of 12 reacted with beta parvalbumin from R. esculenta. Skin prick tests performed with recombinant frog parvalbumin were positive in fish allergic patients. Inhibition studies showed that a fish and frog allergic patient was primarily sensitized to fish parvalbumin. CONCLUSION: Cod parvalbumin, a major cross-reactive allergen among different fish species, shares IgE binding epitopes with frog parvalbumin. This in vitro cross-reactivity seems to be also clinically relevant. Parvalbumins probably represent a new family of cross-reactive allergens.

Allergic cross-reactions between cat and pig serum albumin. Study at the protein and DNA levels.

After observing a patient allergic to cat dander and pork but devoid of other allergies, we prospectively screened patients known to be allergic to cat for a second sensitization to pork. After collecting the sera of 10 young patients found to contain specific IgE to cat dander and pork, we undertook this study to detect the possible cross-reactive allergen, define its molecular characteristics, and evaluate its clinical relevance. Through immunoblotting techniques, cat and porcine serum albumin were found to be jointly recognized molecules. These findings were further analyzed by specific anti-albumin IgE titrations and cross-inhibition experiments. Cat serum albumin cDNA was obtained from cat liver, and the corresponding amino acid sequence was deduced and compared to the known porcine and human serum albumin sequences. Inhibition experiments showed that the spectrum of IgE reactivity to cat serum albumin completely contained IgE reactivity to porcine serum albumin, suggesting that sensitization to cat was the primary event. In two cohorts of cat-allergic persons, the frequency of sensitization to cat serum albumin was found to lie between 14% and 23%. Sensitization to porcine albumin was found to lie between 3% and 10%. About 1/3 of these persons are likely to experience allergic symptoms in relation to pork consumption. Sensitization to cat serum albumin should be considered a useful marker of possible cross-sensitization not only to porcine serum albumin but also to other mammalian serum albumins.