An enzyme-linked immunosorbent assay for the detection of antigen-specific rat immunoglobulin E with improved sensitivity upon a conventional horseradish peroxidase-based ELISA method.

As part of an ongoing project, male Brown Norway rats (67 weeks old) were exposed via the intraperitoneal route to either isolated SLG, semi-skimmed or whole milk (coadministered with carrageenan or alum as IgE-selective adjuvants). Sera isolated at various time points were assa ed for PLG-specific rat IgE, performed using H V an,y/or AChE-based ELISAs. Where necessary, single-tailed paired Student's T-tests were performed. Fi ure 1 demonstrates the,reproducibility of the AChE ELIS1 based upon the analysis of ten serum samples. The validation of the assay is supported b the low errors for each sample. A com arative analysis o?the HRP and AChE ELISAs is presentelin figure 2. The 3 samples shown are representative of a larger panel. Using data obtained from control sera + 3SD as a threshold level, the HRP ELISA can detect PLG-specific rat IgE at a mean dilution of 1/320, whereas the mean level for the AChE-based assay reaches 1/10240. This relates to an increase in sensitilty ,o f approximately 32-fold. Figure 3 demonstrates the application of the optimised AChE ELISA to the analysis of a specific immunisation regimen. A significantly boosted IgE response (P <0.05) occurs at day 42 , which was not as apparent when analysed with the HRP ELISA (data not shown). IgE. Investigation of the e responses however, re uire e specificity of such IgE levels of IgE or a highly sensitive assa metlod. ELISA techniques