Long-term Reproducibility of Allergen-specific IgE Measurements by ImmunoCAP
Sunday, March 4, 2018: 3:00 PM
S310AB (Convention Center)
Robert G. Hamilton, PhD DABMLI FAAAAI, , ,
RATIONALE: Source biological materials used in allergosorbent production vary in specificity/potency from collection/extraction method differences and biological variability stemming from progressive global warming. We have examined variability in ImmunoCAP IgE-antibody (Ab) levels specific for 5 allergen specificities using >100 allergosorbent lots.

METHODS: First, a serum pool containing IgE to multiple allergen specificities was used to quality control (QC) >100 lots of short ragweed (sRW), rye/Bermuda grass, peanut and/or D.-farinae allergosorbents over 10 years of testing. Second, IgE anti-sRW containing sera (range 0.1 to 380 kUa/L, n=100) were used to QC the specificity of 2-lots of sRW-allergorbents manufactured with sRW, collected pre-2015 or 2016-2017 using the same collection area, time-of-year and collection method to assess global warming's impact on allergenic potency.

RESULTS: First, long-term reproducibility was evident by inter-lot coefficients of variation (CVs) of 6.6%-11.5% for 25->100 lots of 5 allergosorbent specificities. Mean QC-IgE-Ab levels spanned 0.9-15.1 kUa/L. Second, the recent 2016-2017 sRW-allergosorbent bound 2.6-fold higher IgE-anti-sRW level (range 0.66-13.3 fold) than pre-2015 sRW-allergosorbent. Interestingly, only 47% of the 100 sRW-specific IgE sera were positive for IgE anti-native Amba1 (IgE-anti-nAmba1/IgE-anti-sRW ratio range=1.2%-172%).

CONCLUSIONS: Despite occasional inter-lot allergosorbent-related shifts >3SD in QC-IgE-Ab results, long-term IgE antibody binding reproducibility was evident over 10 years of observation, with allergosorbent inter-lot CVs < 15%. The 2.6-fold higher IgE-anti-sRW binding capacity using post-2016 sRW-allergosorbents confirms gradual increases in sRW-allergen content used for allergosorbent manufacturing over the ~8 years allergen content has been monitored. Increases in atmospheric CO2 reportedly increase flower production and the magnitude/duration of pollen and allergen output.