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D Kraft

Publications and source records attributed to D Kraft.

368 records · Page 21Linked to original sources
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Cross-reacting allergens in tree pollen and pollen-related food allergy: implications for diagnosis of specific IgE.

BACKGROUND: A number of recombinant allergens are by now constituents of devices that can be routinely used for the detection of specific IgE. Therefore, the results of diagnostic procedures using conventional allergen extracts can be compared with those employing selected recombinant allergens. METHODS: Thirty-four sera from patients allergic to birch pollen were tested with the standard t3-CAP and rBet v 1a- and rBet v 2-CAP. cDNA was prepared by RT-PCR using primers according to the N terminus of purified allergens. Expression cDNA libraries were screened with IgE from selected patients. RESULTS: Twenty-four patients allergic to birch pollen showed the same RAST class with t3 as with rBet v 1a; 8 patients differed within 1 RAST class. In addition, 3 patients showed RAST class 3 with rBet v 2. Besides Bet v 1 and Bet v 2, 3 allergens from celery and avocado belonging to highly conserved protein families were cloned and sequenced. CONCLUSIONS: rBet v 1a can be expected to represent an excellent tool for the diagnosis of patients allergic to birch pollen in Central, Northern, and Eastern Europe. Still, a much higher number of patients has to be tested. For their high degree of conservation, further protein families have to be identified to explain cross-reactivities of birch pollen allergens other than Bet v 1 and Bet v 2 with, e.g., allergens from vegetable food.

Allergens↗
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Enolases are highly conserved fungal allergens.

BACKGROUND: Lack of knowledge of the identity of fungal allergens still is a major obstacle for improvement of diagnosis and therapy of allergies to moulds. We have therefore further analyzed the allergens of the two moulds, Alternaria alternata and Cladosporium herbarum and found that enolases (EC 4.2.1.11) are major allergens, at least of the two fungal species just mentioned. METHODS: The enolases of Alternaria and Cladosporium were cloned from cDNA libraries constructed from vegetative cells of the two moulds by immunological screening with sera from selected patients allergic to the moulds. The two enolases were expressed as recombinant nonfusion proteins and used for determination of the incidence of allergy to enolase among a cohort of patients. RESULTS: Sequencing of the two enolases showed very close relationships with other known fungal enolase sequences. Competition experiments using immunoblots of the recombinant nonfusion proteins showed nearly complete identity of the epitopes on both enolases. Serum from a patient reactive to Cladosporium enolase reacted equally well with the enolases of Alternaria, Saccharomyces and Candida. About 50% each of the sera from patients reactive to Cladosporium and Alternaria were strongly reactive to the recombinant enolases. CONCLUSIONS: Enolases are therefore considered to be highly conserved major fungal allergens.

Allergens↗
PubMedDate not supplied

Isoforms of atopic allergens with reduced allergenicity but conserved T cell antigenicity: possible use for specific immunotherapy.

BACKGROUND: We analyzed the T cell activation potency and the IgE-binding properties (allergenicity) of nine isoforms of Bet v 1, the major allergen of birch pollen. METHODS: The capacity of recombinant Bet v 1 isoforms to bind serum IgE from allergic patients was evaluated by immunoblot experiments and skin prick tests. The potency of Bet v 1 isoallergens to activate T lymphocytes from birch-pollen-allergic patients was assayed using allergen-specific T cell clones. RESULTS: According to their ability to bind IgE from allergic patients in immunoblot experiments, Bet v 1 isoforms can be grouped into high-IgE-binding molecules and molecules with low/no IgE-binding activity. Representatively, isoform d was used in skin tests. Skin prick tests revealed no potency of this isoform to induce wheal and flare reactions in the skin of birch-pollen-allergic individuals. In contrast, isoform a and natural Bet v 1 displayed high allergenicity in vivo. On the other hand, Bet v 1 isoform d (low allergenicity) displayed significant higher T cell activation potency when compared to isoform a (high allergenicity). CONCLUSION: Based on these findings, we propose a new form of specific immunotherapy using hypoallergenic recombinant allergen isoforms.

Allergens↗
PubMedDate not supplied

Division of the major birch pollen allergen, Bet v 1, into two non-anaphylactic fragments.

We have expressed in Escherichia coli two halves of the major birch pollen allergen, Bet v 1. Both fragments representing the complete 17-kD allergen were purified to homogeneity. In contrast to the complete recombinant, Bet v 1, the fragments had almost completely lost their IgE-binding capacity and exhibited a random coil structure as analyzed by circular dichroism. The ability of the recombinant fragments to trigger histamine release from allergic patients' basophils as well as their capacity to elicit skin reactions were also largely abolished. Both non-anaphylactic Bet v 1 fragments carried the majority of T cell epitopes and may therefore be considered as safe tools for immunotherapy of tree pollen and associated food allergy.

Allergens↗
PubMedDate not supplied

Genetically engineered and synthetic allergen derivatives: candidates for vaccination against type I allergy.

Type I allergy, a hypersensitivity disease affecting almost 20% of the population worldwide, is based on the IgE recognition of otherwise harmless antigens (i.e., allergens). Allergen-induced crosslink of effector cell-bound IgE antibodies leads to the release of biological mediators and thus to immediate disease symptoms (allergic rhinitis, conjunctivitis and asthma). Specific immunotherapy, the only causative treatment of Type I allergy, is based on the administration of increasing doses of allergens to allergic patients in order to yield allergen-specific non-responsiveness. Major disadvantages are 1. that current forms of allergen immunotherapy are performed with allergens difficult to standardize which cannot be matched to the patients reactivity profile and 2. that the administration of active allergen preparations can cause anaphylactic side effects. Through the application of molecular biological techniques many relevant environmental allergens have been produced as active recombinant proteins which allow component-resolved allergy diagnosis and thus represent the basis for patient-tailored forms of immunotherapy. Here we review molecular strategies which have been recently applied to generate genetically engineered and synthetic hypoallergenic allergen derivatives for patient-tailored and safe vaccination against Type I allergy.

Allergens↗