Correlation of protein levels with skin prick test reactions in patients allergic to latex.

Abstract

Natural rubber latex (NRL) gloves are the major source of proteins that cause latex allergic reactions in sensitized health care workers and patients. This study evaluated the effect of manufacturing changes on reducing protein, antigen, and allergen levels of latex medical gloves. Three types of NRL gloves were manufactured with a common batch of compounded latex. The NRL gloves were analyzed for total protein by using the American Society for Testing and Materials D5712-95 Lowry method, and specifically for latex proteins by immunoassay. Allergen levels in the extracts were determined by end-point titration skin prick tests (SPTs) on patients allergic to NRL. Extracts from regular powdered gloves had detectable levels of latex proteins and allergens (62% SPT positive), whereas the powder-free gloves were low in protein content and allergenicity (5% to 8% SPT positive). No significant difference in SPT reactivity was observed between the chlorinated powder-free gloves and the polymer-coated gloves. Although the protein levels determined by the Lowry assay correlated with SPT reactivity (r = 0.95), the test was restricted by a high detection limit (9.3 micrograms/ml). Fifty-eight percent of patients allergic to latex reacted at the 50 micrograms/gm detection limit allowed by the Food and Drug Administration. The ELISA had a good correlation with SPT reactivity (r = 0.93), and because of the greater sensitivity, gloves testing below the ELISA reporting limit (0.06 microgram/ml) have a significantly lower potential for eliciting reactions in patients allergic to latex. Results of protein assays are acceptable criteria with which to rate the potential allergenicity of gloves; however, the American Society for Testing and Materials D5712-95 assay may lack the sensitivity to provide clinically relevant data.