Rapid release of Ole e 1 from Olive pollen using different solvents

Background: Solubility is an important characteristic of allergenic molecules. The aim of this study was to investigate the solubility of Ole e 1, a major allergen of Olea europaea, using different solvents. Material and methods: Olea europaea pollen was placed in a glass column and extracted using three different solvents: deionized water, phosphate buffer 0.01 M (PBS) and normal saline (NaCl 0.9%). Several fractions were collected after extraction with each solvent and pooled based on individual protein content. Each fraction corresponded to a different elution profile, as determined by linear regression analysis. After 130 min of extraction, the pollen that remained in the column was further extracted overnight. A control olive pollen extract was also prepared with each solvent. The antigenic and allergenic profiles of all the eluted and pooled fractions were analysed by SDS-PAGE and inmmunoblots. Protein and Ole e 1 content and the amount of protein needed to produce 50% inhibition were also calculated. Ten patients were skin prick tested with the fractions obtained with deionized water. Results: Four elution profiles were obtained using deionized water as the extracting solution and three with the two other solvents. The three solvents produced different kinetics of allergen release. Ole e 1 was rapidly released when water was used, obtaining a total of 256 mug of Ole e 1/ml after only 7 min of extraction (fraction EC1). Using PBS, or NaCl 0.9%, the release of Ole e 1 started after 4 and 9 min of extraction, respectively. The highest amount ofOle e 1 was eluted after 44 and 26 min, with a total concentration of 162 and 203 mug of Ole e 1/ml, respectively. The presence of Ole e 1 in each phase was verified by SDS-PAGE and immunoblot analyses. Conclusions: The extracting solution seems to determine the antigenic profile of olive pollen extracts. Ole e 1 is rapidly released from the pollen grain after extraction in deionized water. The solubility seems to be affected by the use of other solvents. These techniques could be used to manipulate the Ole e 1 content in O. europaea extracts.