NATURAL-RUBBER LATEX SKIN TESTING REAGENTS - SAFETY AND DIAGNOSTIC-ACCURACY OF NONAMMONIATED LATEX, AMMONIATED LATEX, AND LATEX RUBBER GLOVE EXTRACTS

Background: Nonammoniated latex, ammoniated latex, and rubber glove ex tracts are the only sources of natural rubber (Hevea brasiliensis) lat ex that have potential for use as skin testing reagents in the diagnos is of latex allergy. Their diagnostic sensitivity and specificity as s kin test reagents are unknown. Objective: We conducted a phase 1/2 cli nical study to examine the safety and diagnostic accuracy (sensitivity and specificity) of nonammoniated latex, ammoniated latex, and rubber glove extracts as skin test extracts to identify the most efficacious source material for future skin test reagent development. Methods: Tw enty-four adults not allergic of latex, 19 adults with hand dermatitis or pruritus, and 59 adults with a latex allergy were identified by cl inical history. All provided blood and then received puncture skin tes ts and intradermal skin tests with nonammoniated latex, ammoniated lat ex, and rubber glove extracts from Malaysian H. brasiliensis latex by use of sequential titration. A glove provocation test and IgE anti-lat ex RAST were used to clarify positive history-negative skin test respo nse and negative history-positive skin test response mismatches. Resul ts: All three extracts were biologically safe and sterile. After norma lization to 1 mg/ml of total protein, all three extracts produced equi valent diagnostic sensitivity and specificity in puncture skin tests a nd intradermal skin tests at various extract concentrations. Optimal d iagnostic accuracy was safely achieved at 100 mu g/ml for puncture ski n tests and 1 mu g/ml for intradermal skin tests (e.g., nonammoniated latex: puncture skin test sensitivity 96%, specificity 100%; intraderm al ski test sensitivity 93%, specificity 96%). The presence of IgE ant ibody in skin was highly correlated with IgE anti-latex in serum (nona mmoniated latex: r = 0.98, p < 0.001; ammoniated latex: r = 0.94, p < 0.001; rubber glove extract: r = 0.96, p < 0.001). All five available subjects with a positive history, negative skin test response, and abs ence of IgE antibody in serum had a negative glove provocation test re sponse, indicating no clinical evidence of latex allergy. No systemic or large local allergic reactions were observed with puncture skin tes ts or intradermal skin tests. Conclusions: Equivalent diagnostic sensi tivity and specificity were observed with the nonammoniated latex, amm oniated latex, and rubber glove extract skin test reagents after norma lization for total protein; nonammoniated latex may be considered the reagent of choice on the basis of practical quality control and reprod ucibility considerations.