Immunochemical Measurement of Placental Tissue Protein 4 in Serum

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Abstract
Using the avidin-biotin binding system, an enzyme immunoassay procedure was developed to measure the placental tissue protein 4 (PP4) in serum. The standard curve covered the range from 0.5 to 100 ng/ml of PP4. The intra- and inter-assay coefficients of variation were less than 5 and 10%, respectively. Recoveries of PP4 added to serum ranged between about 99 and 105%. The result obtained by this assay method correlated well with those obtained by the radioimmunoassay method. The PP4 serum level was under 10 ng/ml in non-pathological individuals. In pregnancies during 5-40 weeks, the level ranged from 0.98 to 15.0 ng/ml. In ovarian malignancies, the PP4 concentration in serum irrespectively scattered from 0.9 to 21 ng/ml. Significantly high PP4 levels were found in uterine cervical cancer in the early stage and also in endometrial cancer.