Parvalbumin, the major fish allergen, is recognized by allergen-specific IgE of more than 90% of all fish-allergic patients. A detailed knowledge of allergenic structures is crucial for developing a vaccine inducing blocking antibodies specifically directed towards the IgE binding epitopes. In the present study we aimed to use the phage display technique to generate mimotopes, which mimic epitopes on parvalbumin. Parvalbumin-specific IgE was purified from sera of fish-allergic patients and used for screening of a constrained decamer phage library. After four rounds of biopanning using parvalbumin-specific IgE, five phage clones were selected which were specifically recognized by parvalbumin-specific IgE as well as IgG. DNA sequencing and peptide alignment revealed a high degree of sequence similarities between the mimotopes. Interestingly, on the surface of natural parvalbumin three regions could be defined by computational mimotope matching. In accordance, previously defined allergenic peptides of cod parvalbumin highlighted areas in close proximity or overlapping with the mimotope matching sites. From the presented data we conclude that our approach identified conformational epitopes of parvalbumin relevant for IgE and IgG binding. We suggest that these mimotopes are suitable candidates for an epitope-specific immunotherapy of fish-allergic patients.

Allergens↗

PubMed2005

Plasma levels of polyunsaturated fatty acids in children with atopic dermatitis and in atopic and nonatopic controls.

BACKGROUND: Atopic dermatitis has been thought to be associated with a disturbance in n-6 polyunsaturated fatty acid (PUFA) metabolism, but randomized trials investigating the clinical efficacy of oral supplementation with gammalinolenic acid have revealed conflicting results. AIM OF THE STUDY: To re-investigate the proposed linkage between PUFA dysregulation and atopic dermatitis. MATERIALS AND METHODS: Plasma levels of linoleic acid (LA), gammalinolenic acid (GLA), dihomogammalinolenic acid (DGLA) and arachidonic acid (AA) were measured using HPLC in 22 children with atopic dermatitis. Patients were subdivided into those with elevated total serum IgE (group A, n = 15, IgE > +1 SD of age-specific normal values) and those with normal IgE (group B, n = 7) and compared with children suffering from allergic rhinitis/asthma (group C, n = 8) and with non-atopic controls (group D, n = 6). RESULTS: GLA levels were significantly lower (p < 0.05) in eczema patients with elevated IgE (A, 0.19 +/- 0.06%) and in atopic controls (C, 0.23 +/- 0.06%) than in eczema patients with low IgE (B, 0.42 +/- 0.19%) and non-atopic controls (D, 0.43 +/- 0.16%). There were no significant differences between groups for LIN, DGLA and AA, except for lower LIN levels in atopic controls. Correlation of individual LA and GLA values showed significantly steeper regression lines in low-IgE responders (B and D, k(x) = 0.058) than in high-IgE responders (A and C, k(x) = 0.012; p < 0.02), suggesting impaired delta-6-desaturase function in the latter. For the study population as a whole, there was a clear negative correlation between total levels of IgE and GLA (r(s) = -0.64) and a moderate negative correlation between total IgE and AA (r(s) = -0.38). CONCLUSIONS: Dysregulation of n-6 PUFA metabolism is neither consistently found in nor specifically associated with atopic dermatitis but rather appears to be associated with IgE production and atopy in general. The finding of decreased GLA levels in eczema patients with elevated total IgE and in children with allergic rhinitis and asthma but not in eczema patients with normal total IgE questions the proposed pathophysiologic role of fatty acid dysregulation in atopic dermatitis.

Asthma↗

PubMed2004

[Adverse reaction to the azo dye Pigment Red 170 in a tattoo].

A 30-year old white male presented with sharply demarcated pruritic lesions in a black and red tattoo on his wrist. The strongly infiltrated and slightly scaly eruptions started four months after tattoo application and were notably restricted to the red-colored areas. Symptoms got worse after UV exposure. Patch testing and photo patch testing with the used azo dye Pigment Red 170 (C.I. 12475) was negative. Histology revealed lichenoid dermatitis without signs of a granulomatous reaction. The verification of allergic sensitization in hypersensitivity reactions to tattoos by patch testing may be difficult due to the poor penetration into the skin of the applied azo pigments. Intradermal testing may be more sensitive but bears the risk of long lasting skin reactions.

Adult↗

PubMedDate not supplied

Patch testing in children, adults, and the elderly: influence of age and sex on sensitization patterns.

Patch testing was done on 2776 consecutive patients (76.5% female) with a locally revised standard series of 34 contact allergens and the results analyzed for age- and gender-specific differences. At least one positive epicutaneous test reaction occurred in 48.9% of patients. Nickel (20.9%), ethylmercuric chloride (13.2%), thimerosal (11.8%), fragrance mix (9.3%), metallic mercury (8.9%), palladium (5.8%), balsam of Peru (3.8%), copper (3.7%), cobalt (3.3%), and chromium (2.3%) were the 10 most important sensitizers. The following tested allergens with sensitization rates of more than 1% were not part of the usual standard series: ethylmercuric chloride, metallic mercury, copper, propolis (1.3%), propylene glycol (1.0%). Reactions to nickel, cobalt, and palladium, but not to chromium, were significantly more abundant in females (p < 0.002, chi-squared test). The overall sensitization rate was highest in children less than 10 years old (62%) and decreased steadily, to be lowest among patients more than 70 years old (34.9%). The rate of positive reactions to nickel and thimerosal decreased with age, while fragrance mix and metallic mercury stayed at the same level through all age groups.

Adolescent↗

PubMedDate not supplied

Histamine intolerance-like symptoms in healthy volunteers after oral provocation with liquid histamine.

Histamine in food at non-toxic doses has been proposed to be a major cause of food intolerance causing symptoms like diarrhea, hypotension, headache, pruritus and flush ("histamine intolerance"). Histamine-rich foods such as cheese, sausages, sauerkraut, tuna, tomatoes, and alcoholic beverages may contain histamine up to 500 mg/kg. We conducted a randomized, double-blind, placebo-controlled cross-over study in 10 healthy females (age range 22-36 years, mean 29.1 +/- 5.4) who were hospitalized and challenged on two consecutive days with placebo (peppermint tea) or 75 mg of pure histamine (equaling 124 mg histamine dihydrochloride, dissolved in peppermint tea). Objective parameters (heart rate, blood pressure, skin temperature, peak flow) as well as a total clinical symptom score using a standardized protocol were recorded at baseline, 10, 20, 40, 80 minutes, and 24 hours. The subjects received a histamine-free diet also low in allergen 24 hours before hospitalization and over the whole observation period. Blood samples were drawn at baseline, 10, 20, 40, and 80 minutes, and histamine and the histamine-degrading enzyme diamine oxidase (DAO) were determined. After histamine challenge, 5 of 10 subjects showed no reaction. One individual experienced tachycardia, mild hypotension after 20 minutes, sneezing, itching of the nose, and rhinorrhea after 60 minutes. Four subjects experienced delayed symptoms like diarrhea (4x), flatulence (3x), headache (3x), pruritus (2x) and ocular symptoms (1x) starting 3 to 24 hours after provocation. No subject reacted to placebo. No changes were observed in histamine and DAO levels within the first 80 minutes in non-reactors as well as reactors. There was no difference in challenge with histamine versus challenge with placebo. We conclude that 75 mg of pure liquid oral histamine--a dose found in normal meals--can provoke immediate as well as delayed symptoms in 50% of healthy females without a history of food intolerance.

Administration, Oral↗