Biological equilibration of allergen preparations: methodological aspects and reproducibility.
A 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 less than 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 less than 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.
Department of Paediatrics, University Hospital, Linköping, Sweden.
S
S
Dreborg
A
A
Basomba
L
L
Belin
S
S
Durham
R
R
Einarsson
N E
NE
Eriksson
A B
AB
Frostad
O
O
Grimmer
R
R
Halvorsen
M
M
Holgersson
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000592:standards*; D004306:Dose-Response Relationship, Immunologic; D006632:Histamine / Q000008:administration & dosage; D006801:Humans; D008875:Middle Aged; D011852:Radioallergosorbent Test; D012882:Skin Tests / Q000379:methods
D000485:Allergens; D006632:Histamine