Stability and potency of raw and boiled shrimp extracts for skin prick test

Abstract

© 2015, Allergy and Immunology Society of Thailand. All rights reserved. Background: The difference of stability between raw and boiled shrimp extracts used in prick tests has never been investigated despite its potential consequences in tests development. The aim of this study was to compare the raw and boiled shrimp extracts of two species; Macrobrachium rosenbergii (freshwater shrimp) and Penaeus monodon (seawater shrimp) held at 4 ºC for different periods of time for their stability and potency in vivo by using the skin prick test (SPT) method. Methods: Raw and boiled M. rosenbergii and P. monodon extracts were prepared and stored at 4 ºC for 1, 7, 14 and 30 days. Thirty patients were pricked with raw and boiled shrimp extracts at all storage times, as well as prick to prick skin test (PTP) to fresh raw and boiled shrimps of both species. The mean wheal diameter (MWD) resulting from prick tests for all shrimp extracts was measured and compared. Results: The shrimp extracts of all storage times yielded positive skin test results in the range of 90%-100%. Raw P. monodon extracts induced larger wheals than boiled extracts at all storage times. There was no significant difference of MWD between raw and boiled M. rosenbergii extracts on day 1, 7, and 14. Significant correlations between MWD of PTP to fresh shrimps and SPT to all shrimp extracts were observed. All shrimp extracts were sterile at all storage times. Conclusions: Raw and boiled M. rosenbergii and P. monodon extracts were stable and sterile at 4 ºC for at most 30 days. SPT with these extracts induced more than 10 mm in shrimp allergy patients and the results were comparable with PTP to fresh shrimps.