Skin prick test reactivity to recombinant latex allergens

Allergy to latex has become a serious and increasingly common health problem, particularly for healthcare workers and patients who undergo frequent surgical procedures. Testing for latex allergy currently involves in vitro tests and skin prick testing using crude preparations of natural rubber latex (NRL). To date, 10 latex proteins have received designation as allergens (Hev b 1 to Hev b 10) and, except for Hev b 4, have been cloned as recombinant proteins. Our aim was to compare the skin prick test (SPT) reactivity of six recombinant latex allergens with SPT reactivity to natural rubber latex proteins in known latex-allergic individuals.

Six recombinant proteins were expressed in Escherichia coli, and tested as the intact fusion proteins (Hev b 2, 5, 6, 8) or as purified proteins (Hev b 3 and 7). SPT with the six recombinant latex allergens was performed using 10-fold serial dilutions on 31 latex-allergic subjects to determine the level of reactivity to each recombinant allergen. Latex-specific IgE was determined using the AlaSTAT assay.

All six recombinant allergens were reactive by SPT in at least 1 latex-allergic patient but not in any of the control patients. The frequency of sensitization to the various recombinant allergens was similar to previous studies using the native proteins isolated from NRL. The minimal level of protein for a positive skin test was 70 pg/ml for NRL and 1 ng/ml for one recombinant allergen (Hev b 7). In our patients, the use of a combination of recombinant latex allergens Hev b 5, 6 and 7 diagnosed latex allergy with 93% sensitivity and 100% specificity.

Recombinant latex allergens are clinically reactive, can be produced in a standardized manner, and could potentially provide safe, sensitive and specific reagents for the diagnosis of latex allergy.