Competitive immunoassay for antigenic latex protein measurement: rabbit antiserum-based assay compared to modified Lowry and human IgE-inhibition methods.

A new rabbit antiserum-based assay was designed and evaluated for the assessment of the allergen potency of latex medical gloves, since total protein measurement by modified Lowry method remains unsatisfactory and the human IgE-inhibition method is limited by the use of sera from type I allergic patients. Four rabbit sera against a nonammoniated latex extract were shown by immunoblotting to have similar binding patterns to those obtained by human IgE. One rabbit serum was used to develop a competitive immunoassay for antigenic latex proteins (CIALP). The same nonammoniated latex extract was used for coating and calibration. The lower detection limit of the method was 0.085 microgram/g of glove. Antigenic proteins measured by CIALP for 77 latex glove extracts (33 pairs of surgical gloves and 11 exam gloves) showed positive correlation with those of the modified Lowry method (r = 0.4; p < 0.001). For 36 extracts made from the right and the left hand of 18 out of the 33 surgical latex gloves tested, inhibition of human specific-IgE results did not correlate with the modified Lowry method but did with the CIALP results (r = 0.8, p < 0.0001). The CIALP, which is well correlated with the human IgE-inhibition test, enables the assessment of the allergenicity of latex medical gloves by measuring the antigenic proteins.