FUNDAMENTAL STUDIES OF THREE RADIOIMMUNOASSAY KITS MEASURING PROSTATIC ACID PHOSPHATASE (PAP) CONCENTRATIONS

Measurement of prostatic acid phosphatase (PAP) concentration is useful for the diagnosis and treatment of prostatic cancer. Fundamental studies of measurement of PAP concentration by radioimmunoassay were performed and values determined by three commercially available kits were compared, those are, PAP EIKEN RIA Kit (E kit), RIA Quant P.A.P. (M kit) and GammaDab PAP RIA Kit (C kit). Upper limits of normal PAP concentration were 3 ng/ml by E and M kits and 2 ng/ml by C kits, respectively. The reproducibility and the recovery studies of three kits were satisfactory. However, dilution curve of some patients was not strait. PAP concentration of 27 patients measured by three kits were correlated well to each other, but the discrepancy of values was noticed in high PAP concentrations. PAP concentration measured by RIA is more reliable than that by enzyme immunoassay. When keeping serum samples, the effect of time, temperature and frreze and thawing on PAP values was obvious. It is recomended that serum is separated at 4℃ as soon as possible after collecting blood and kept frozen until use.