Quality assurance of the basophil activation test
For a sustained high-quality use of BAT in the clinical setting, constant quality control, as laid out in ISO 15189:2012, ISO15189:2013 and ISO 9001:2016, is necessary and increasingly required by national legislation. For the test to be reimbursed by health care systems and insurance companies, rigorous quality assurance process needs to be in place in certified laboratories.
Representatives of European laboratories developing basophil testing have discussed opportunities of basophil testing since 200698,99, and have met regularly in the EUROBAT meeting series to strengthen the development of basophil tests. These meetings continue every second year under the auspices of the Interest Group Allergy Diagnosis and Systems Medicine within EAACI. To meet the increasing demand for certification described in ISO 9001/15189 for biomedical laboratories, the European Academy of Allergy and Clinical Immunology launched a task force with the aim of standardizing basophil testing and establishing external quality assurance under the control of EAACI. Engaging EAACI as the European organisation representing professionals working with allergy in quality assurance of a cutting-edge diagnostic test would uniquely enhance the quality of the test. To our surprise, standardizing the method of analysis dramatically improved coherence of the results (CV <10% for detection of CD63+ basophils) in ten European laboratories31, suggesting that the standardization of reagents used may be of minor importance. As this is in stark contrast to the heterogeneity of results obtained in external quality assurance of IgE testing100, it is important to maintain the momentum of this process and bring it to IgE testing as well.
At the present time, in the United States, there are 9 laboratories in 6 states, that provide BAT for the common food allergens with an inter-laboratory quality assurance system in place and harmonized protocols. Similar to its European counterpart, AmeriBAT was created between these laboratories that offer clinical grade BAT to establish a network of quality assurance and control (QA/QC). In this quarterly process, a blood sample from Donor A is processed the day it is collected (Day 0) in Lab 1 and then mailed to lab 2 where it is processed the following day (Day 1) and a blood sample from Donor B is processed in lab 2 on Day 0 and mailed to Lab 1 for processing on Day 1. The temperature during shipping is measured with a temperature strip to ensure that the sample is within 2-37C range. The %CV between the results for the two locations should be below 25% but results as high as 35% can be accepted as basophils can be considered rare events in whole blood.