Naslov
Assay of biological activity of ragweed pollen extract in the skin of sensitive patients

Autori
Stipić Marković, Asja ; Sket-Janković, Neva ; Čvorištec ; Branimir ;

Izvornik
Periodicum biologorum (0031-5362) 91 (1989); 57-57

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, kratko priopcenje, znanstveni

Ključne riječi
allergen extract, Histamine equivalent potency, biological unit

Sažetak
The potency of allergy preparation to produce local anaphylatic reaction varies considerably between different source for materials. The aim of biological standardization (BS) is to establish a unit indicating a similar alergenic activity for all species (2, 3). The Committee on Alergen Standardization within the Scandinavian Society of Allergology proposed the use of skin prick testing (SPT) as a simple method for BS (3, 4). They also proposed the unit for alergen potency: 1 HEP (Histamine Equivalent in Prick testing) equal to 1000 biological units per ml (BU/ml). The unit represents the concentration of an alergen, eliciting skin reaction (in samples of patients clinically sensitive to this allergen) of the same size as that provoked by histamin 1 mg/ml. The purpose of this study was to determine the total biological activity of a partly purified, lyophilised pollen ekstrakt Ambrosia Elatior (AE). Extract of pollen allergen was obtaind from the manufacturer (Institute for Imunobiology and Virusology „Torlak“, Belgrade). It contains less than 3 % of pollens of other species. The extract was prepared by extraction in NaCl –phosphate buffer (extraction ratio 1/10 w/v), in cold water for 24 hours af h After filtration the extract was dialysed in bufer saline twice during 24 h (the proteins with the molecular weight of 5000-150 000 Daltons were excluded). On the day of testing, the allergen was reconstituted with further diluted with diluent (50% glycerine in saline), to obtain six tenfold concentrations(10-2, 10-1, 10- 1, 101, 102, 103 μ/ml). SPT were performed on the radial side of the forearm with each dilution, as previously reported (5). Histamine HCL 1 mg/ml was used as positive reference, together with diluent as negative control. The wheal diameters were recorded and for each allengen concentration the relative diameters in percent of the patient's own histamine wheal were calculated. Thirty four highly sensitive subjects were included in the Investigation.The criteria where: a well-defined positive clinical history, positive SPT, high titer of specific IgE (Phadebas RAST class 3 or 4), no immunotherapy with the allergen in question, and the mean wheal diameter after SPT with histamine equal to or greater than 4 mm. The results of testing with six concentrations of AE preparation and histamine are presented in Figure 1. Clearly, allergen biological activity and the skin corresponds to the applied concentration, and there is an evident dose- response relationship (p<0.001). The preciation of the SPT as expressed by the coeficient of variation (CV) was (from the lowest to the greatest concentration) 59%, 33 %, 28%, 18%, 18% end and for histamine 16%. Calculation of the regression lines to test the dose-response relationship between di intensity of skin reaction (Y) and the allergen concentration (X) were carried out in 4 mathematical models: Y=axX+b, Y=axlogX+b, logY=axX+b and logY=axlogX+b. The most compatible was to log/log and lin/log modals. The mean coefficient of correlation for the tested group of patients vere estimated to be: 0.94007 (lin/lin), 0.98641 (lin/log), 0.90513 (log/lin), 0.98834 (log/log). The coefficients of 0.98641 and 0.98834 are accepted as statistically significant correlation (p<0.001). Allergen concentration which elicits skin reaction equivalent to dose of histamine (HEC-Histamine Equivalent Concentration) was determined for each patient. The individuel HEC values were distributed cver the following range: 109.13 – 498.61 μg/ml, with the median of 172.33 μg/ml. This amount of dry material represents the allergenconcentration with the poency of 1000 BU/ml. Based on the present results we consider that the measurement of allergenic potency by skin test is a good method which provides much information on alergen extract and Is, therefore sutable for the standardization of commercial preparations. References 1. Aas K, Backman A, Belin L, Weeke B 1987 Standardization of Allergen Extract with Appropriate Method. Allergy 33: 130 2.Dreborg S, Belin L, Eriksson NE, Grimmer O, Kunkel G, Malling HJ, Nilsson G, Sjogrej J, Zetterstrom O 1987 Results of biological standardization with standardized allergen preparations, Allergy 42:106 3. Dreborg S, Holgersson M, Nilsson G, Zetterstrom O 1987 Dose-response relationship of alf alergen, histamine and histamine realisers in skin prick test and precision of the skin prick test method allergy.Allergy 42:117-125 4.Nordic Guidelines. Registration of Allergen Preparations.Nordic Council of Medicies, Uppsala, 1982 5.Stipić Marković Asja, Sket Janković Neva, Čvorištec Branimir, Matijević Ljubica, Tuđman Zdenko Dekaris Dragan 1986 Reevalution by biological standardization of known allergenic potency of an Dactylis glomerata extract.Period Biol 88:198-199

Izvorni jezik
Engleski

Znanstvena područja
Kliničke medicinske znanosti

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