The renin-angiotensin system in patients with repeated anaphylactic reactions during hymenoptera venom hyposensitization and sting challenge

Patients with a history of anaphylactic reactions to hymenoptera venom who tolerated the hyposensitization and the sting provocation without problems (n = 10) had angiotensin I (ANG I), angiotensin II (ANG II), angiotensinogen and renin similar to the values found in healthy nonallergic controls (n = 11). In contrast, patients who repeatedly experienced anaphylactic reactions during hyposensitization and who displayed anaphylactic reactions to sting provocation with a living insect (n = 6) showed significantly lower renin (p < 0.05), angiotensinogen (p < 0.05), ANG I (p < 0.05) and ANG II (p < 0.05) plasma levels as compared to healthy nonallergic controls (n = 11). Sting provocation with a living insect induced clinical symptoms of anaphylaxis in all of the 6 patients. A decrease in ANG I was found in 4 of the patients (67%) after provocation as compared to the concentration before the sting challenge. Angiotensinogen decreased in 3 of the patients (50%) whereas renin activity decreased in 2 of the patients (29%), In all cases a decrease in ANG II was noticed (100%). It is concluded that patients at high risk of developing anaphylactic reactions possess a dysfunctional renin-angiotensin system (RAS) which is not stimulated and does not respond appropriately. These findings point to an important role of the RAS as a defense mechanism in response to anaphylactic reactions.