Diagnostic value of three different latex extracts.

The diagnosis of latex allergy is made on clinical history, but a confirmatory skin prick test (SPT) or a serological assay based on a commercial latex extract is always recommendable. Different raw materials can be used in the preparation of commercial latex extracts. Such extracts can consequently show both different qualitative profiles and a different diagnostic potential. Therefore, the selection of a proper latex extract is essential for in vitro and in vivo diagnosis of latex allergy. In the present study three different latex extracts, prepared from different raw materials (ammoniated -AL-, serum -SL-, or rubber particles -RPE- latex), are compared by in vitro techniques using sera from twenty patients with latex allergy. SDS-PAGE technique was used to compare the antigenic profile of the three latex extracts. Subsequently, their allergenic profiles were evaluated by immunoblotting technique using the individual sera from the twenty latex allergic patients. The diagnostic potential of the three latex extracts was also evaluated using direct Radio-Allergo-Sorbent Test (RAST) as well as skin prick tests (SPTs). In order to establish the more appropriate latex extract in a perspective of in vivo diagnosis of latex sensitization, the same latex extracts were subsequently compared by an in vivo SPT involving ten of the above subjects. The SDS-PAGE profiles of the three latex extracts examined were quite different. SL extract showed numerous bands comprised between 10-100 kDa. RPE extract was characterized by two intense bands at 14 and 20 kDa while AL extract showed the poorer antigenic composition. Analogously, immunoblotting analysis evidenced a different profile in relation to both different patients and extracts. For only two out of the twenty sera, direct RAST results showed a same positive class in relation to the different latex extracts used. SPT with SL extract showed, in respect to the other extracts (AL, RPE), a significantly higher wheal. This study showed that SL extract is able to express the best in vitro and in vivo diagnostic potential. Thus, its use should be preferred for the diagnosis of patients affected by latex allergy.