Background: To study the mechanisms of passive sensitization of patients receiving plasma containing IgE antibodies to a defined allergen.
Methods: When required for medical reasons, regular donor plasma with IgE antibodies to timothy grass allergen (8-205 kU(A)/l), was given. Kinetics of IgE antibodies in the recipients' serum and his/her basophil allergen threshold sensitivity, CD-sens, was monitored up to 2-3 weeks after transfusion. The IgE antibodies were quantitated by ImmunoCAP. The CD-sens in plasma recipients, determined by CD63 up-regulation, was measured by flow cytometry and compared to CD-sens of patients with allergic asthma and/or rhinitis.
Results: There was a significant correlation (r = 0.98; P < 0.001) between amount of IgE antibody given and recipient serum peak concentration. The T(1/2) for IgE antibody in circulation was 1.13 days (95% confidence limit 0.35-1.91 days). The recipients became CD-sens positive already 3 h after transfusion. The CD-sens peak was observed after 3.4 days and the value were correlated (r = 0.68; P < 0.02) to the amount of IgE antibody transfused and were of the same magnitude as found in allergic patients. The T(1/2) of CD-sens indicated two populations of basophils; one with a CD-sens decrease T(1/2) of 4 days and one of 10 days.
Conclusion: Transfused IgE antibodies will sensitize mast cells and basophils to CD-sens levels similar to those of allergic patients. The recipients expressed 'slow' or 'rapid' CD-sens decline, indicating two different basophil populations. After transfusion of plasma with >10 kU(A)/l IgE antibody the recipient could have allergen reactive basophils for up to 7 weeks.