Cut-off value of D. pteronyssinus specific IgE in double negative patients Der p 1 and Der p 2 and its clinical repercussion

Abstract

Accessibility to more precise diagnostic techniques such as component resolved diagnostics (CRD), provides us with an important advance in diagnostic aspects as well as treatment. The subject of this study aims to better understand the profiles of sensitization to Der p 1, Der p 2 and Der p 23 and to know to what extent their use could help us in optimizing the decision-making for their treatment with Specific Immunotherapy. Cross-sectional study of subjects older than 5 years, diagnosed with allergy to HDM using skin prick test and sIgE, with symptoms of rhinitis and/or asthma. Total and specific IgE was determined to D. pteronyssinus, nDer p 1, rDer p 2 and rDer p 23 using ImmunoCAP. 240 patients were recruited (97.1% rhinitis and 46.25% rhinitis and asthma). Four different phenotypes were observed: positive or negative for sIgE nDer p 1 and/or IgE rDer p 2. 17% of these patients sIgE were double negative for Der p 1 and Der p 2 (increasing with age and with significantly lower sIgE levels than the rest of the groups). Using ROC curves, value less than 2.18 KU_A/L for D. pteronyssinus sIgE gave us a sensitivity and specificity of 0.882 and 0.985, respectively, to double negative IgE nDer p 1 and IgE rDer p 2 group. Despite positive SPT and sIgE to D. pteronyssinus, 17% of the studied population is IgE nDer p 1 and IgE rDer p 2 double negative, with a cut-off value of 2.18 KU/L, which is very relevant for taking of decisions in prescription of AIT. The double positive population sIgE nDer p 1 and IgE rDer p 2 is associated with asthma compared to the other groups and this does not seem to be influenced by IgE rDer p 23.

Figure 1

Prevalence of sensitization and levels of IgE in the different phenotype studied. (a) Prevalence of sIgE reactivity to rDer p 1, rDer p 2 in HDM allergic patients in southern o Spain (n = 240). (b) Mean value of sIgE D. pteronyssinus to each phenotype. Bar shows statistical difference between phenotype. P-value < 0.05. (c) ROC curve about total IgE D. pteronysssinus. Cut-off point from which the complete extract-specific IgE valor is positive, but IgE nDer p 1 and IgE rDer p 2 will be negative.

Figure 2

Distribution of the different phenotype in function of the age. Bar means statistical difference p-value < 0.05.

Figure 3

Graphic representation of sIgE nDer p1 and sIgE rDerp2 value for each patient. In the graphic is represented lineal correlation and R² valor. Correlation Pearson = 0.53567; Correlation Spearman = 0.54864.

Figure 4

sIgE median value to different components of D. pteronyssinus for each phenotype studied.

Figure 5

Rhinitis/asthma distribution for each phenotype. (a) Percentage of patient in each group suffering rhinitis (no)/rhinitis + asthma (Yes). (b) p-value using different statistical adjust model. When the p-value is lower than 0.05 in the three type of adjust, the sample are considered statistically difference.