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

BACKGROUND: Natural rubber latex (NRL) gloves are the major source of proteins that cause latex allergic reactions in sensitized health care workers and patients. OBJECTIVE: This study evaluated the effect of manufacturing changes on reducing protein, antigen, and allergen levels of latex medical gloves. METHODS: 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. RESULTS: 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 μg/ml). Fifty-eight percent of patients allergic to latex reacted at the 50 μg/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 μg/ml) have a significantly lower potential for eliciting reactions in patients allergic to latex. CONCLUSIONS: 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. (J Allergy Clin Immunol 1996;98:1097-1102.)