Service Communautaire d'Information sur la Recherche et le Développement - CORDIS

RBL/LAD2 as alternative diagnostic tests

In only one case of milk allergy a mediator release was observed to milk allergen extracts and skin prick test solution. It appeared that not all sera were able to sensitize RBL cells. Thus in this system there are non-responders, which theoretically also may be due to wrong or irrelevant proteins, or because commercially available extracts (from Sigma Aldrich) do differ from naturally occurring proteins.

However, non-responders have also been described in other cellular tests, such as the histamine release test. For egg allergic patients, in 11/19 patients a mediator release could be detected. Release was higher for single allergens, such as albumine as compared to collective extracts (e.g. hen's egg allergen) and for skin prick tests. In the 11 positive sera, eight were tested with allergen-reduced egg and a reduction of mediator release of a factor of >1000 was found.

In some sera, the flat curve to normal egg allergen compromised detailed analysis of the reduction factor, however, a drastic reduction of allergenicity was found in all sera. The human mast cell line of a patient with leukemia (LAD2) carries a functional human receptor FceR1and was evaluated for its use for food allergy in parallel to the RBL cells. Best results were achieved, when high antibody concentrations of anti-IgE were taken (1µg/ml).

As for most patients, a 1:20 dilution of serum gave good results, we tested serum of four patients with milk and/or egg allergy. We were able to degranulate mast cells of this cell line by preincubation of serum of allergic patients and incubation with anti-IgE antibodies, as well as by incubation with cow's milk and hen's egg allergens.

Reported by

Department of Dermatology and Allergology
Biederteiner Strasse 29
80802 München
Germany
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