TRYPTASE AND HISTAMINE-RELEASE DUE TO A STING CHALLENGE IN BEE VENOM ALLERGIC PATIENTS TREATED SUCCESSFULLY OR UNSUCCESSFULLY WITH HYPOSENSITIZATION

Background Hyposensitization with bee venom leads to full protection i n most, but not all patients with IgE-mediated systemic reactions to b ee stings. Objective To determine the relationship of clinical reactiv ity to the release of mediators and to changes of antibody concentrati ons in the peripheral circulation at a bee sting challenge test. Metho ds Blood was sampled before (0 min) and at 15, 60 and 180 min after a sting challenge from 19 patients on hyposensitization. Of these, six s till reacted and 13 were protected. Histamine, mast cell, tryptase, be e venom-specific IgE and IgG in the serum, and histamine release from peripheral blood leucocytes (PBL) upon exposure to bee venom were dete rmined. Results Tryptase above the detection level was found only at 1 5 (60) min in 4/6 (1/6) patients who reacted. After the sting challeng e there was a significant increase of the histamine levels in patients who reacted at 15 min (P < 0.05) and in patients who did react at 60 and 180 min (P < 0.01). The total histamine content of PBL was signifi cantly decreased after 15 and 60 min in patients who reacted (P < 0.01 ) and in those that did not (P < 0.05). Bee venom-induced histamine re lease was significantly reduced in patients reacting and those that di d not at 15 min (P < 0.05), and was significantly decreased in reactor s also at 60 and 180 min (P < 0.05/0.01). Specific IgG antibodies show ed a minor decrease (P < 0.05) after the sting challenge in both group s, whereas specific IgE did not change significantly. Conclusion These results indicate that bee venom anaphylaxis is associated with the re lease of mediators from both mast cells as well as basophils. Successf ul hyposensitization does not induce a state of immunological non-reac tivity, but rather alters the magnitude and the pattern of mediator re lease.