Is sounds like the patient had anaphylaxis to venom and has been on AIT. Retesting was negative to HS and “somewhat positive to ALK” reagents. My guess would be that there is some slight variability between extracts or related to the testing site/technique. You would have to look at the PI of both material to makes sure the same allergens are in the venom tested. If I remember correctly, several years ago there was a death of patient on VIT and the lawsuit reveled that one supplier had different YJ species than another supplier and the argument was that the patient died because the A/I did not include all possible allergens. A second thought would be that VST are not always positive and a follow up sIgE to venoms must be done to confirm the negative response.
I have essentially switched all my venom patients to HS over the past year or so because of the ALK issue. I have not performed head to head testing to see if there is any significant difference between testing materials.
Andrew Murphy, MD, FAAAAI