Evaluation and Comparison of Commercially Available Latex Extracts for Skin Prick Tests

Background: Crude latex extracts are commonly used in skin prick tests (SPT) for the diagnosis of natural rubber latex (NRL) allergy. Nevertheless, variations in protein and allergen composition between latex extracts from different manufacturers can hamper a correct diagnosis. Objectives: To analyze the heterogeneity of proteins and allergens in latex extracts from 7 different manufacturers and to assess its relevance in the diagnosis of latex allergy. Methods: Seven latex SPT extracts were analyzed for protein content using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The 4 major allergens Hey b 1, Hey b 3, Hey b 5, and Hey b 6.02 were also quantified using enzyme immunoassay. All commercial extracts were tested for their in vitro allergenic capacity using microarray inhibition assays and for their ability to induce biological reactivity in latex-allergic patients undergoing SPT. Results: The protein content of the extracts varied widely from 8.0 mu g/mL to 526.5 mu g/mL. SDS-PAGE revealed broad differences in protein profiles between the extracts. Marked variability in the contents of all 4 major allergens was observed, and Hey b 3 and Hey b 5 were undetectable in some extracts. Microarray inhibition assays and SPT demonstrated relevant differences in allergenic capacity between the extracts. Conclusions: The marked heterogeneity in protein and allergen content of latex extracts from different manufacturers could explain the broad spectrum of SPT results recorded. Our findings suggest that the extracts used for the diagnosis of latex allergy should be improved and standardized.