Human Leukocytes Contain Angiotensin I, Angiotensin II and Angiotensin Metabolites

Angiotensin I (ANG I) and angiotensin II (ANG II) were measured radioimmunologically in human leukocytes extracted with a mixture of acetone, 1N HCl and water (40:1:10 vol). The analytical recoveries of 125I-ANG I and 125I-ANGII, which were added prior to extraction, were 92.00 ± 3.I0 and 99.19 ± 0.91% (mean ± SEM; n = 12). The concentration of ANG I- and ANG II-like material in leukocytes from healthy volunteers was 32.04 ± 3.64 and 13.05 ± 1.26 fmol/mg protein (n = 24). The immunoreactive material could be characterized on HPLC as Ile5-ANG I, Ile3-ANG II and angiotensin metabolites such as Ile4-ANG III, Ile3-ANG II hexapeptide, Ile2-ANG II pentapeptide and Ile1-ANG II tetrapeptide. From the ANG I-immunoreactive material determined in the extracts, 26% could be characterized on HPLC as Ile5-ANG I. The ANG II-immunoreactive material present in the extracts could be separated on HPLC into 44% Ile5-ANG II, 14% Ile4-ANG III, 7% Ile3-ANG II hexapeptide, 4% Ile2-ANG II pentapeptide and 8% Ile1-ANG II tetrapeptide. Patients with a history of anaphylactic reactions to bee or wasp venom showed significantly reduced ANG II concentrations in their leukocytes as compared to controls (6.76 ± 0.76 fmol ANG II/mg protein, n = 22, vs. 13.05 ± 1.26 fmol ANG II/mg protein, n = 24; p < 0.05). A significant correlation between the severity of clinical symptoms and the ANG II levels was found for grade I and II reactions (p < 0.05). Successful immunotherapy induced a 5-fold increase in ANG II as compared to controls (61.85 ± 9.73 fmol ANG II/mg protein, n = 16, vs. 13.05 ± 1.26 fmol ANG II/mg protein, n = 24; p < 0.05) and a 9-fold increase as compared to patients without immunotherapy (61.85 ± 9.73 fmol ANG II/ mg protein, n = 16, vs. 6.76 ± 0.76 fmol ANG II/mg protein, n = 22; p < 0.05).