Radioimmunoassay of group II pepsinogen in human serum.

A new radioimmunoassay (RIA) using a double antibody method for human Group II pepsinogens in serum was developed. (1) Sensitivity of this assay system was of the order of 1 microgram per 1 of serum and optimal assay range was 10 to 50 microgram per 1; (2) no effect of interference of human serum was detected and there was no cross-reaction with human Group I pepsinogens within the optimal assay range; (3) satisfactory results were obtained for both within- and between-assay reproducibility (coefficient of variation was 3.9% and 3.7-15.3%, respectively); (4) the mean (+/- SEM) serum Pg II level in healthy donors was 15.9 +/- 0.7 microgram/l for males and 12.8 +/- 1.3 microgram/l for females; the difference between males and females was statistically significant (p less than 0.05); (5) the mean serum Pg II level in 10 patients with total gastrectomy was 1.2 +/- 0.05 microgram/l. These results suggest that most of Pg II in human serum is derived from the gastroduodenal system.