# Pollen Food Allergy Syndrome in Southern European Adults: Patterns and Insights
## 4 Diagnostic Tools for the Assessment of PFAS  
In vitro and in vivo IgE-detection is the cornerstone of daily allergy practice. Skin Prick Testing (SPT) is a practical, fast, and cost-effective method for assessing allergen sensitivity. The use of raw extracts in food allergies can indicate sensitization by food allergens but does not identify the allergen molecules (components) responsible for symptoms. In contrast, SPT extracts containing panallergens, like profilin, can be a useful tool. A study analyzing commercial SPT extracts of food and pollen (including a profilin extract) using SDS-PAGE, revealed inconsistent profilin content across pollen SPT extracts, and its absence in peach SPT extracts from two different suppliers [72]. This suggests that SPT has limited utility in detecting PFAS.  
The in vitro detection of specific IgE (sIgE) with extract-based diagnostics, is considered slightly less sensitive than SPT and cannot distinguish between multiple genuine sensitizations and cross-sensitizations. However, component-resolved diagnostics (CRDs) have been developed to detect allergenic molecules. The CRD enhances the accuracy of PFAS diagnosis by identifying primary sensitivities from cross-reactivity. Incorporating molecular diagnostics and CRDs into routine clinical practice is critical for improving diagnostic precision and effectively managing complex multisensitization profiles [73].  
In the era of CRDs, IgE microarrays containing many different allergen components can provide information on the whole IgE sensitization pattern and help the clinician in the diagnosis of components responsible for PFAS. The ImmunoCAP ISAC test is the most used and studied multiplex array to date, offering 112 molecular components. The ALEX\({}^{2}\) multiplex array is a relatively new multiplex allergy test that analyzes more than 120 allergen extracts and 170 molecular components [74]. Advanced tools of informatics, called expert systems, have been developed to support the interpretation of allergy tests based on microarray technology [75]. Such state-of-the-art technology can assist allergy diagnosis of cross-reactions in polysensitized patients [67].  
Region-specific diagnostic and therapeutic approaches are essential for managing PFAS. In Mediterranean countries, molecular diagnostics targeting nsLTPs (e.g., Pru p3)--which are strongly associated with systemic reactions--along with profilins and PR-10 proteins, should be prioritized. Updated knowledge about regional exposomes is crucial for the development of newer, improved, versions of microarrays. Given the current product characteristics, if a comparison should be made, the ISAC is highly reliable but may not cover as many allergens as the ALEX\({}^{2}\) multiplex array and tends to focus more on inhalant allergens than food allergens. ALEX\({}^{2}\) appears to be a preferred method for establishing the diagnosis of PFAS.  
Biotechnology plays a crucial role in diagnosing PFAS; however, the clinician's ability to establish clinical suspicion and set the final diagnosis remains essential, particularly in areas where there is no access to CRDs. A validated questionnaire can be a valuable tool for allergologists [76]. By combining a patient's anamnesis with available diagnostic methods, clinicians can provide accurate information and guidance to the patient.