Six hundred patients with pollen allergy answered a questionnaire about food hypersensitivity. Hypersensitivity to various nuts, fruits and roots was reported more often by patients with birch pollen allergy (70%) than by patients without birch pollen allergy (19%). The stronger the skin test reaction to birch pollen, the higher was the incidence of food hypersensitivity. A negative correlation was found between grass pollen allergy and food hypersensitivity. In the diagnosis of springtime hayfever, the presence of hypersensitivity to nuts, fruits and roots supports a diagnosis of birch pollen allergy.

SummaryA method for biological equilibration (BE) of allergen reference preparations using the skin‐prick test (SPT) method and histamine HCl 10 mg/ml as reference substance (reference method), was evaluated. The precision was low for weals less than 10 mm2. The slope (log weal area/log concentration) of allergen and histamine did not vary significantly between investigators and allergens. The median slopes were 0.39 (n= 384) and 0.34 (n= 397), for allergen and histamine, respectively (P < 0.01). The concentration of allergen eliciting a weal of the same size as that of histamine HCl 1 mg/ml (Chl) in the median sensitive patient, 1000 Biological Units/ml (BU/ml), did not vary significantly between clinics/geographical regions (grasses, mites and moulds). As BE is repeatable between regions. BUs estimated by this method are generally valid. A high correlation (r= 0.91, P < 0.001) was found between the median Chl as estimated with histamine 1 and 10 mg/ml as reference substance, respectively. Thus, this reference method for BE is valid. The precision of the SPT method with histamine HCl 1 mg/ml is not as good as with 10 mg/ml, which is therefore recommended as the reference concentration.

The aim of biological standardization (BS) is to equilibrate the activity (potency) of allergen extracts from different source materials. This was done by performing skin prick tests (SPT) on patients who were sensitive to one of the following 10 allergens: Birch, alder, hazel, timothy, rye grass, velvet grass, cultivated rye, mugwort, D. farinae and Cladosporium herbarum. Patient sensitivity varied within a range of three to four powers of ten for each allergen investigated. The weal size in each patient corresponding to that elicited by histamine 1 mg/ml was calculated using the model log (mean weal diameter) = a + b log (concentration). The correlation coefficients of the regression lines of the allergen dose response relationship were found to be greater than 0.85 in most cases. The median slope for all extracts was 0.24. The slope for Cladosporium was significantly steeper than that for pollens. The amount of material in microgram dry weight (d.w./ml) equal to 1000 biological units/ml (BU/ml) varied within a factor of three between species for all tested purified allergen preparations but Cladosporium. For Cladosporium, about 30 times more material was needed than for D. farinae. When using crude rather than purified material, it was necessary to use five to ten times more to elicit a reaction corresponding to 1000 BU/ml, but the difference was significant only for Cladosporium. The narrow range of allergen concentrations used by us as well as other investigators does not assure positive skin prick test results in all patients with clinical symptoms due to the allergen in question. Skin prick testing should therefore be done over a wide range of concentrations to improve the methods for BS.

The efficiency of the new screening tests for atopy, Phadiatop and CAP Phadiatop, was studied by comparing their results with a clinical diagnosis of atopy in 100 consecutive adults with asthma and/or rhinitis. Further, the diagnostic efficiency of a combination of Phadiatop and a few standardized questions was studied. The Phadiatop was found to have a specificity of 0.98, and a sensitivity of 0.92 and the CAP Phadiatop a specificity of 0.94 and a sensitivity of 0.96. When the Phadiatop was combined with a few questions, a sensitivity of 1.00 was achieved. It is concluded that Phadiatop and CAP Phadiatop have a higher diagnostic precision than other hitherto used methods for screening of atopic allergy. The place of Phadiatop in a diagnostic flow chart is suggested.

Summary In sixty‐five patients with asthma or allergic rhinitis, intracutaneous tests and provocation tests were performed with birch pollen, timothy pollen and/or dog epithelium allergen. The clinical diagnosis was compared with RAST results obtained with identical allergen preparations for in vivo as well as in vitro testing in two different laboratories. An overall correlation between in vitro and in vivo diagnosis was found in 85% of the cases. It is suggested that a scoring system using the sum of case history score and RAST values could be used for screening allergic patients with different allergens, making in vivo tests necessary only in a limited number of the cases.

Among adult patients with bronchial asthma and/or allergic rhinitis undergoing allergological investigation with skin test, nasal provocation test and RAST, 1129 answered a questionaire regarding food sensitivity (FS). 276 (24%) of the patients reported some kind of allergic symptoms on eating or handling various foods, of which hazel nut, apple and shell fish were the most often named. Females reported FS more often than males. A correlation was found between birch pollen allergy and FS with nuts, apple, peach, cherry, pear, plum, carrot and new potato. The higher the degree of birch pollen allergy, according to skin test, RAST or provocation test, the higher the frequency of FS. A correlation was found too between acetylsalicylic acid intolerance and FS with some foods, e.g. nuts, strawberry, almond, green pepper, hip, chocolate, egg, cabbage, milk and wine. The connection between birch pollen allergy and FS is probably explained by the structural relationship between birch pollen allergen and some allergens of the foodstuffs, whereas the high incidence of FS in acetylsalicylic acid-intolerant patients is probably explained by additives in foods as well as salicylates or benzoates naturally occurring in some food.

In 2,368 consecutive adult patients with asthma and/or rhinitis the incidence of positive skin prick test (SPT) with a chironomid extract (CHIR) (produced from "red feather mosquito larvae" used as fish food) was 14% (26% in atopics and 4% in non-atopics). RAST with chironomid was positive in 4% of 110 consecutive sera (8% in atopic sera). Significant correlations were found between RAST and SPT results with chironomid and between SPT results with CHIR and with various crustaceans. Correlations were also found reciprocally among SPT results with different crustaceans and between some crustaceans and moluscs (clam and oyster) as well as among RAST results with chironomid, shrimp and crab. Inhibition experiments showed that chironomid extracts inhibited RAST with shrimp, and vice versa. It is concluded that Chironomidae might be allergens of clinical importance in asthma and rhinitis in Sweden, that cross-allergy exists between chironomids and shrimp and that cross-allergy also might occur among chironomids, crustaceans and molluscs.

The results of skin tests (ST) were compared with those of 2,055 provocation tests (PT) in 403 adult patients with asthma and/or allergic rhinitis. The overall agreement between ST and PT results was 77%. Various correlation figures were found for different allergens. In patients with pronounced allergy in the shock organ the proportion of positive ST was higher than in those with low-grade allergy. It is concluded that only strong ST reactions should be relied upon. In other cases additional diagnostic methods are recommended. The diagnostic precision of ST is of the same order of size as that of the radioallergosorbent test.