Cross-inhibition ELISA of serum IgE reactivity with different grass pollen extracts. Serum numbers are given on the top right of each row and the target grass pollen extract with botanical subfamilies are given for each column of graphs. Inhibitors were added to diluted sera from 0.05 to 50 μg/ml (red triangle symbol, Bahia grass; orange inverted triangle symbol, Johnson grass, pink diamond symbol, Bermuda grass, blue square symbol, Ryegrass, light blue circle symbol, Timothy grass and * Peanut extract; a non-grass pollen, allergen control). Data is expressed as the percentage inhibition of uninhibited IgE reactivity with standard errors for three technical replicates shown. The relative avidity of interaction between serum IgE and a target grass pollen is indicated by the maximum level of inhibition achieved with 10 fold excess of pollen inhibitor in solution over target solid-phase pollen allergen, as well as the concentration of pollen inhibitor required to block 50% (IC50; indicated dotted line) of IgE reactivity. Pooled data from four of these donors for inhibition of IgE reactivity with Bahia and Ryegrass pollen was published in reference 21.