The en 455-3 modified lowry assay does not yield a reliable estimate of the allergenicity level of latex gloves with low total protein content.

Background: Estimation of the allergenicity of latex gloves by measurement of total extractable protein content with the modified Lowry method is not satisfactory. Therefore, complementary methods that are accurate, sensitive, and clinically relevant are needed. The Competitive Immunoassay for Antigenic Latex Proteins (CIALP) method described in a previous study could be a reliable complementary method for estimating the allergenicity of latex gloves.

Material/methods: Extracts from 62 powdered or powder-free gloves (16 surgical and 46 examination) were tested by the EN 455-3 modified Lowry assay, IgE-inhibition, and CIALP. The results were compared with those from 36 glove extracts reported in a previous study.

Results: Significant correlations were observed between CIALP, IgE-inhibition, and the Lowry assay for the 62 glove extracts (r between 0.79 and 0.87; p<0.001), mostly rich in proteins. After inclusion of results from the previous study, significant correlations between the three methods were again observed (r between 0.76 and 0.90; p<0.001). However, there was no correlation between CIALP or IgE-inhibition and results of the Lowry assay for gloves that had a total protein content <50 micro g/g of glove. Furthermore, 15/16 extracts with undetectable total proteins were positive in both the CIALP and IgE-inhibition methods.

Conclusions: The modified Lowry assay alone is useful for estimating the allergenicity of latex gloves when the total protein content is >/=50 micro g/g of glove. For gloves with a total protein content <50 micro g/g of glove, complementary methods such as CIALP are necessary.