Histamine, tryptase, norepinephrine, angiotensinogen, angiotensin-converting enzyme, angiotensin I and II in plasma of patients with hymenoptera venom anaphylaxis.

Markers of immediate-type hypersensitivity such as histamine and tryptase were measured in the plasma of nonallergic volunteers and patients with a history of hymenoptera venom anaphylaxis. No significant differences in histamine or tryptase were found between patients and controls. Norepinephrine, an important compound involved in the control of cardiovascular functions and blood pressure, was the same in patients and nonallergic volunteers. In addition, components of the renin-angiotensin system were determined. Patients with hymenoptera venom anaphylaxis showed significantly lower plasma angiotensinogen concentrations as compared to healthy nonallergic controls (p < 0.007), whereas plasma ACE activity was the same. Likewise, the plasma levels of angiotensin I and angiotensin II were significantly reduced in patients as compared to controls (p < 0.04 and p < 0.003, respectively). These findings suggest that the renin-angiotensin system may play an important role as a counteracting factor in hymenoptera venom anaphylaxis.