Reliability of histamine release test in dust mite allergy: influence of the degree of sensitization.

The histamine release test has been proven to be a very useful method for in vitro diagnosis of IgE-mediated allergy to inhalant and food allergens, as well as for the immunotherapy follow-up of the allergic patient. The aim of the present study was to assess the influence of the degree of sensitization in allergic patients sensitive to Dermatophagoides pteronyssinus on their dose-response curves in histamine release tests. To achieve this aim, we studied 109 D. pteronyssinus allergic patients and 25 healthy control subjects. Intracutaneous skin test, D. pteronyssinus-specific and total IgE quantitations, and histamine release tests were carried out in all the patients. In the case of the histamine release test, five D. pteronyssinus extract concentrations were used (2822.5, 282.25, 28.22, 2.82 and 0.28 UBE/ml), and two patterns of histamine release in sensitive patients were found: one with maximal histamine release at the highest antigen concentration (group I) and the other with maximal release attained at lower concentrations (group II). A sensitization score was designed, after the results from specific IgE and intracutaneous skin tests. There were significant differences (p < 0.05) in antigen-specific and total IgE levels, and in papule diameters and sensitization scores, between the control group and groups I and II. Both groups showed significantly higher (p < 0.05) histamine releases than the control group in response to anti-IgE antibodies. When stimulating the cells with anti-IgE antibodies, histamine release in group II was higher than in group I, although this difference was not significant. Finally, the best correlation between sensitization score and antigen-specific histamine release was found at the 2.82 UBE/ml concentration (r = 0.84, p < 0.001).