Component-Resolved Diagnosis of American Cockroach (Periplaneta americana) Allergy in Patients From Different Geographical Areas

Abstract

<b>Background:</b> Manifestation of respiratory allergy to American cockroach (<i>Periplaneta americana</i>) is prominent in the subtropical and tropical areas. However, co-existing perennial indoor inhalant allergies frequently compromise clinical diagnosis of cockroach allergy, and the analysis of sensitization pattern is limited by the lack of <i>Periplaneta</i> allergens widely available for component-resolved diagnostics (CRD). <b>Objective:</b> To evaluate a collection of previously described recombinant <i>Periplaneta</i> allergens for CRD in cockroach allergy. <b>Methods:</b> A panel of nine recombinant <i>Periplanet</i>a allergens (Per a 1-5, 7-10) was generated, purified, and subjected to physicochemical characterization by applying circular dichroism (CD) spectroscopy, dynamic light scattering (DLS), amino acid (AA) analysis, and mass spectrometry (MS). Patients (<i>n</i> = 117) from India, Korea, Venezuela, and Iran, reporting perennial respiratory indoor allergies with IgE sensitization to cockroach (<i>P. americana and/or Blattella germanica</i>), were included. The sensitization profile was monitored by the experimental ImmunoCAP testing. <b>Results:</b> ImmunoCAP testing confirmed IgE sensitization to <i>Periplaneta</i> and/or <i>Blattella</i> extract in 98 of 117 patients (<i>r</i> = 0.95). Five out of 117 patients were sensitized to only one of the two cockroach species. Within the whole study group, the prevalence of sensitization to individual allergens varied from 4% (Per a 2) to 50% (Per a 9), with the highest IgE values to Per a 9. Patients from four countries displayed different sensitization profiles at which Per a 3 and Per a 9 were identified as major allergens in India and Korea. <i>Periplaneta</i>-derived lipocalin and myosin light chain were characterized as new minor allergens, designated as Per a 4 and Per a 8. <i>Periplaneta</i> extract showed higher diagnostic sensitivity than all individual components combined, suggesting the existence of allergens yet to be discovered. <b>Conclusion:</b> Utilization of a panel of purified <i>Periplaneta</i> allergens revealed highly heterogeneous sensitization patterns and allowed the classification of lipocalin and myosin light chain from <i>Periplaneta</i> as new minor allergens.