Preanalytical temperature and storage stability of specific IgE antibodies in serum.

Allergen-specific serum immunoglobulin E (sIgE) levels are a cornerstone in allergy diagnostics. While immunoglobulins are known to be relatively stable molecules, the influence of preanalytical factors on the stability of sIgE is not thoroughly investigated. We studied the effect of several preanalytical factors: (1) delayed centrifugation of serum samples in tubes with separating gel for 10, 24 and 48 h, (2) prolonged storage at 5 °C for 3, 7, 10 and 14 days, (3) storage tube type (primary tube with separating gel or secondary tube), (4) repeated freeze-thawing cycles, and (5) prolonged storage at -20 °C for 4 and 8 weeks. We found that sIgE is stable at room temperature for 48 h before centrifugation and for 10 days at 5 °C after centrifugation. There was no effect of the separating gel after storing serum for 1 week in the freezer. However, storage for 4-8 weeks, and introducing more than one freeze-thaw cycle resulted in a larger variation of sIgE levels. In conclusion, we found that sIgEs are stable under various preanalytical conditions, which allows for flexible handling of samples for a comprehensive portfolio of sIgE analyses.