<P>Summary</P><P>Background</P><P>Allergic rhinitis (AR) is a very common disease and a risk factor for allergic asthma. The discovery of new biomarkers for the early detection of AR would improve the clinical outcomes and reduce socio-economic burden. We sought to identify a novel serologic marker for detection of AR using a proteomic approach.</P><P>Methods</P><P>To identify the proteins involved in AR, comparative proteomics was applied using nasal lavage fluids (NLFs) taken before and after a nasal provocation test (NPT) with <I>Dermatophagoides pteronyssinus</I> (<I>Dpt</I>) in a subject with AR sensitized to <I>Dpt</I>. The clinical relevance of the identified proteins was evaluated by ELISA using NLFs and sera from the three study groups: <I>Dpt</I>-sensitive AR; asymptomatic <I>Dpt</I>-sensitive controls; and non-atopic healthy controls. The sensitivities and specificities of the candidate proteins for predicting AR were determined using receiver operating characteristic (ROC) curves.</P><P>Results</P><P>In proteomic analysis, lactoferrin expression was up-regulated after NPT. The validation study using ELISA showed a significantly lower serum lactoferrin level in the AR group than those of the other two groups (<I>P</I><0.05, respectively). To discriminate between subjects with or without AR, the optimal serum cut-off level of lactoferrin was set at <307 ng/mL using the ROC curve. The sensitivity and specificity for predicting AR were 81.4% and 58%. When combined with serum <I>Dpt</I>-specific IgE level, the sensitivity and specificity for predicting AR were 76.7% and 79.2%.</P><P>Conclusion</P><P>These results suggest that the serum lactoferrin level is associated with the phenotype of <I>Dpt</I>-sensitive AR, and in combination with the serum <I>Dpt</I>-specific IgE level, may be a potential serologic marker for early detection of AR.</P><P><I>Cite this as</I>: G.-S. Choi, S.-Y. Shin, J.-H. Kim, H.-Y. Lee, N. S. Palikhe, Y.-M. Ye, S.-H. Kim and H.-S. Park, <I>Clinical & Experimental Allergy</I>, 2010 (40) 403–410.</P>
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