Different results of plasma 6-keto-prostaglandin F1 alpha measurements utilizing two antisera with apparently similar specificity.
While developing a radioimmunoassay for the measurement of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) in human plasma, we obtained two antibodies which had apparently similar cross-reactivities with 22 other prostaglandins and related compounds. However, in radioimmunoassay, use of one of the antibodies gave results which were about double the results obtained with the other. The results obtained by both antibodies correlated significantly with each other according to the equation y = 0.43x - 13.0 pg/ml, R = 0.89, n = 58 (p less than 0.001). The increments of plasma 6-keto-PGF1 alpha after an intravenous infusion of prostacyclin (PGI2) also correlated with the dose of PGI2 (R = 0.93 and 0.96, n = 24, p less than 0.001) in both cases, and the increments obtained by the use of both antibodies correlated with each other (R = 0.94, n = 24, p less than 0.001). The increments were, however, of different magnitude. These differences can be best explained by assuming different immunoreactivity of the two antibodies with metabolites of PGI2 other than 6-keto-PGF1 alpha, or with the two known stereochemical configuration of 6-keto-PGF1 alpha.
D015121:6-Ketoprostaglandin F1 alpha / Q000097:blood*; D000918:Antibody Specificity; D006801:Humans; D011863:Radioimmunoassay / Q000379:methods
D015121:6-Ketoprostaglandin F1 alpha