Performance of methods for the measurement of natural rubber latex (NRL) proteins, antigens and allergens☆

Abstract Rationale Determination of natural rubber latex (NRL) allergenic proteins in medical and consumer products promotes rational selection of products to minimize sensitization. The objective of this multi-center study was to assess the variability and relative analytical performance of available laboratory methods to measure NRL proteins. Methods Extracts from powdered and powder-free latex medical gloves (n=30, 5ml PBS/G, agitation-2hr), were analyzed for total protein (ASTM D5712 Modified Lowry-4 labs), antigenic proteins using rabbit antisera (ASTM- D6499-2 labs; LEAP-1 lab), total allergens using latex-specific human IgE antibody (RAST/ELISA Inhibition Assays-6 labs) and for individual H. brasiliensis allergens Hev b 1,3,5,6.02 using monoclonal antibodies (FITkit-7 labs). Precision profile analysis evaluated intra- and inter-laboratory variability and inter-method comparability. Results The sum of the 4 Hev b allergen monoclonal assay values displayed the highest correlation with RAST/ELISA inhibition values for total allergen, which were considered most reflective of the extractable latex allergen content from gloves (r 2 =0.91-0.95). The total protein levels as measured with ASTM D5712 Modified Lowry method showed the next best correlation with RAST/ELISA inhibition assay generated allergen content (r 2 =0.79-0.85). While results of the LEAP and D6499 latex antigen assays correlated well with one another (r 2 =0.92), they were less reflective of glove allergen content compared to RAST/ELISA inhibition assay results. Conclusions Good agreement between the combined Hev b 1,3,5,6.02 content and the allergen level as assessed by human IgE-based RAST/ELISA inhibition assays, suggests that that monoclonal antibody-based immuno-enzymetric assay analysis may be a useful indicator for the allergen content of NRL products.